Sleep
The importance of dark at night
02/Feb/13 03:13 PM
by Kate Whimster, BCom, MIFHI, ND
I’d like to share with you a fantastic episode of The Nature of Things called Lights Out! that succinctly and powerfully demonstrates the effect on our health from exposure to light at night.
Background:
We all have a “body clock”, or circadian rhythm and light is a major signal that keeps us “on time.” A part of the brain called the superchiasmatic nucleus prompts the pineal gland to produce melatonin when we are exposed to darkness. This hormone, melatonin, affects many other systems of the body during darkness when we sleep. Then, when we are exposed to light again in the morning, melatonin drops and our daytime functions begin.
This daily rhythm is very important and has a major impact on health and disease. It is only relatively recently (the last 130 years) that human beings have disrupted this rhythm via being indoors during the day and had so much exposure to light at night.
We’ve long known that shift workers face many more health risks just by virtue of the disruption to circadian rhythm caused by working at night and conversely, the Amish, who don’t use electricity, have much lower levels of obesity (despite a high caloric intake and high saturated fat intake), heart disease, metabolic syndrome, and depression. Aren’t we lucky to have such diverse populations to study for such information?
I’ve highlighted several areas this program explored with regards to how exposure to light at night affects health:
Cancer risk:
1. Become Amish. Is it possible to convert to or join the Amish? Or, you could stop using electricity, eat only foods you grow and prepare, and engage in lots of character-building physical labour. If this doesn’t interest you, keep reading.
2. Prioritize your circadian rhythm:
Want to learn more?
I highly recommend the book Lights Out: Sleep, Sugar, and Survival by T.S. Wiley for more information about how light and dark signals affect our health. You can also check out a previously blog I wrote about the connection between sleep and metabolic syndrome.
I’d like to share with you a fantastic episode of The Nature of Things called Lights Out! that succinctly and powerfully demonstrates the effect on our health from exposure to light at night.
Background:
We all have a “body clock”, or circadian rhythm and light is a major signal that keeps us “on time.” A part of the brain called the superchiasmatic nucleus prompts the pineal gland to produce melatonin when we are exposed to darkness. This hormone, melatonin, affects many other systems of the body during darkness when we sleep. Then, when we are exposed to light again in the morning, melatonin drops and our daytime functions begin.
This daily rhythm is very important and has a major impact on health and disease. It is only relatively recently (the last 130 years) that human beings have disrupted this rhythm via being indoors during the day and had so much exposure to light at night.
We’ve long known that shift workers face many more health risks just by virtue of the disruption to circadian rhythm caused by working at night and conversely, the Amish, who don’t use electricity, have much lower levels of obesity (despite a high caloric intake and high saturated fat intake), heart disease, metabolic syndrome, and depression. Aren’t we lucky to have such diverse populations to study for such information?
I’ve highlighted several areas this program explored with regards to how exposure to light at night affects health:
Cancer risk:
- Breast cancer incidence and mortality is highest in industrialized countries where exposure to light at night is highest.
- Human breast cancer cells implanted into mice exposed to light round the clock grew into measurable tumours quickly, while tumours did not appear in control mice who had 12 hours of darkness.
- Tumours in mice perfused with human blood samples taken from women exposed to light were much more active and grew faster than tumours perfused with blood samples from women exposed to dark.
- 20 years of night shift work was associated with a 79% increase in risk of breast cancer! Wow.
- Shift work that disrupts circadian rhythm is likely carcinogenic (cancer-causing) in human beings! Shift work is in the same risk category as anabolic steroids, UV light exposure, and diesel engine exhaust.
- Mice exposed to light at night gained 20% more (!) body mass than controls with the same caloric intake.
- Eating later at night leads to weight gain via disrupted metabolism - so that rule of thumb to eat lighter at night and stop eating several hours before bed is really good advice!
- Mice kept in the dark at night had a survival rate after heart attack of nearly 100% while in mice exposed to just 3 nights of dim light (such as we humans may be exposed to in a hospital setting overnight with all the monitors and machines!), survival rates dropped to just 30-40%.
- Mice exposed to chronic low levels of light at night exhibited a loss of interest in things they normally had enjoyed (one major sign of depression).
- On a positive note, these effects are highly reversible in a short period of time when darkness at night is restored, so there is hope for you if you’re feeling down - turn out the lights!
1. Become Amish. Is it possible to convert to or join the Amish? Or, you could stop using electricity, eat only foods you grow and prepare, and engage in lots of character-building physical labour. If this doesn’t interest you, keep reading.
2. Prioritize your circadian rhythm:
- Accept your status as a human being - to function well you need both light and dark exposure and a minimal amount of sleep and it is your responsibility to ensure you get what you need.
- Most research shows that health is optimal when people get at least 7-8 hours quality sleep per night consistently, so plan your day and night to give yourself this important rest.
- Black out your windows with opaque blinds or curtains.
- Get rid of night lights already! And cover sources of light, such as clocks and electronics.
- Wear a sleep mask to cover your eyes and block out light.
- Eliminate sources of blue light in the evening, such as TVs, computers, and other electronics that can suppress melatonin production for up to 90 minutes! So yes, the advice to avoid electronics at night is also true!
- Keep lights dim and warm in the evening using different lamps or dimmers.
- Emphasize red light at night, such as using candlelight or fire. Also good for romance!
- If you wake during the night, avoid bright lights (including those cursed electronics) and if you must have light, stick to dim red-toned light.
- Get outside in the light for at least 20 minutes per day.
- Use more blue light during the day, such as the light from compact fluorescent light bulbs.
- Seriously consider if shift work is right for you, and if not, start taking steps to change your work schedule.
- Plan a sleep schedule that ensures you get consistent undisturbed sleep when you are not working.
- Sleep in complete darkness and observe other tips for sound sleep.
- There appears to be some benefits to increasing light (ideally blue) while working and shifting to less light (and warmer colours, like red) once finished work to simulate nighttime.
- However, there is also research which aims to prevent the changing of the circadian rhythm in shift workers by reducing exposure to blue light which also shows benefit.
Want to learn more?
I highly recommend the book Lights Out: Sleep, Sugar, and Survival by T.S. Wiley for more information about how light and dark signals affect our health. You can also check out a previously blog I wrote about the connection between sleep and metabolic syndrome.
Comments
Tips for sound sleep
07/Aug/12 08:10 AM
by Kate Whimster, BCom, MIFHI, ND
In the past few months I’ve done several presentations that include information about the importance of sleep (for more about booking me for speaking engagements, including several example topics, check out my Speaking page). The first step for better sleep is to follow some simple tips:
5 Tips for Sound Sleep
1. Darkness (and light)
Sleeping in TOTAL darkness maximizes melatonin (the hormone your brain makes to put you to sleep) production which helps you get to sleep easier, sleep more deeply, and wake at the appropriate time in the morning. It is equally important to get some light exposure in the morning to send your body the right signals of light and dark. This daily rhythm is associated with proper hormone balance, energy during the day, blood sugar balance, and many other aspects of health.
Dim the lights in the evening and then remove or cover all sources of light in your bedroom (window, clock, electronics, night lights) and then get outside for 15-20 minutes each morning.
2. Timing is everything
Try to maintain consistent sleep and wake times within 1-2 hours of variation. The most important time to be sleeping according to Traditional Chinese Medicine and for optimal restoration is between 11pm and 1am. Sleeping late and waking late just does not give you the same rest and messes up those night/day signals to your body.
Also, avoid exercising 3 hours before bed - exercising later than this can interfere with normal sleep cycles.
3. Eat (and drink) for better sleep
Avoid eating within 3 hours before sleep and avoid drinking liquids within 2 hours before sleep. Sleep time is so important for blood sugar control and can be a major help for weight loss, so you don’t want to interfere with this by being overfull or waking to urinate.
Alcohol may make you feel sleepy but it actually shortens sleep time and inhibits deep sleep. Stimulants (like caffeine, chocolate, nicotine, and sugar) also interfere with sleep. If you have chronic sleep issues (troubling getting to sleep, staying asleep, or waking too early in the morning), it can be very helpful to eliminate alcohol, caffeine, chocolate, sugar, and nicotine completely for 4-6 weeks. Many people are completely unaware of how sensitive they are to these substances and how much they can affect sleep so experiment with yourself to find out!
4. Healthy sleep habits
Avoid electronics (phone, computer, TV, etc) before bed (they are too stimulating and the light they emit interferes with melatonin production) and instead do a relaxing activity before bed, such as reading, a warm bath, or meditation/breathing techniques. Check out my blog on Breathing for a simple technique to try.
Avoid napping during the day - if you need a nap because you are tired, that is a sign your nighttime sleep is not optimal and you should do something about it! If you must nap, keep it short (20-40 minutes).
Finally, choose an alarm you like. Waking up every morning to an annoying sound is not a great way to ensure a stress-free day! There are many wonderful alarms that play music or wake you up using progressive lighting. There’s also a great app for iPhone (and maybe other phones) called Sleep Cycle Alarm which measures your movement at night to determine where you are at in your sleep cycles and then wakes you at a time when it is best within a window you set.
5. What if I still can’t sleep?
If you can’t fall asleep or wake in the night, keep the lights low, avoid electronics, and do something relaxing, such as breathing or meditation. If you have trouble falling asleep due to thoughts or worries, keep a pen and paper by your bed and write down all the things you are thinking about so you can deal with them the next day. Sometimes just getting things down on paper can make a huge difference.
If you have chronic sleep issues or want to improve your sleep, there are many naturopathic treatment options available to treat your individual situation.
In the past few months I’ve done several presentations that include information about the importance of sleep (for more about booking me for speaking engagements, including several example topics, check out my Speaking page). The first step for better sleep is to follow some simple tips:
5 Tips for Sound Sleep
1. Darkness (and light)
Sleeping in TOTAL darkness maximizes melatonin (the hormone your brain makes to put you to sleep) production which helps you get to sleep easier, sleep more deeply, and wake at the appropriate time in the morning. It is equally important to get some light exposure in the morning to send your body the right signals of light and dark. This daily rhythm is associated with proper hormone balance, energy during the day, blood sugar balance, and many other aspects of health.
Dim the lights in the evening and then remove or cover all sources of light in your bedroom (window, clock, electronics, night lights) and then get outside for 15-20 minutes each morning.
2. Timing is everything
Try to maintain consistent sleep and wake times within 1-2 hours of variation. The most important time to be sleeping according to Traditional Chinese Medicine and for optimal restoration is between 11pm and 1am. Sleeping late and waking late just does not give you the same rest and messes up those night/day signals to your body.
Also, avoid exercising 3 hours before bed - exercising later than this can interfere with normal sleep cycles.
3. Eat (and drink) for better sleep
Avoid eating within 3 hours before sleep and avoid drinking liquids within 2 hours before sleep. Sleep time is so important for blood sugar control and can be a major help for weight loss, so you don’t want to interfere with this by being overfull or waking to urinate.
Alcohol may make you feel sleepy but it actually shortens sleep time and inhibits deep sleep. Stimulants (like caffeine, chocolate, nicotine, and sugar) also interfere with sleep. If you have chronic sleep issues (troubling getting to sleep, staying asleep, or waking too early in the morning), it can be very helpful to eliminate alcohol, caffeine, chocolate, sugar, and nicotine completely for 4-6 weeks. Many people are completely unaware of how sensitive they are to these substances and how much they can affect sleep so experiment with yourself to find out!
4. Healthy sleep habits
Avoid electronics (phone, computer, TV, etc) before bed (they are too stimulating and the light they emit interferes with melatonin production) and instead do a relaxing activity before bed, such as reading, a warm bath, or meditation/breathing techniques. Check out my blog on Breathing for a simple technique to try.
Avoid napping during the day - if you need a nap because you are tired, that is a sign your nighttime sleep is not optimal and you should do something about it! If you must nap, keep it short (20-40 minutes).
Finally, choose an alarm you like. Waking up every morning to an annoying sound is not a great way to ensure a stress-free day! There are many wonderful alarms that play music or wake you up using progressive lighting. There’s also a great app for iPhone (and maybe other phones) called Sleep Cycle Alarm which measures your movement at night to determine where you are at in your sleep cycles and then wakes you at a time when it is best within a window you set.
5. What if I still can’t sleep?
If you can’t fall asleep or wake in the night, keep the lights low, avoid electronics, and do something relaxing, such as breathing or meditation. If you have trouble falling asleep due to thoughts or worries, keep a pen and paper by your bed and write down all the things you are thinking about so you can deal with them the next day. Sometimes just getting things down on paper can make a huge difference.
If you have chronic sleep issues or want to improve your sleep, there are many naturopathic treatment options available to treat your individual situation.
Stress management talk July 4th
19/Jun/12 03:42 PM
by Kate Whimster, BCom, MIFHI, ND
Unfortunately, I had to cancel this talk (originally scheduled on June 13th) due to illness, but I’m pleased that I have been able to reschedule it to July 4th!
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, July 4th, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
See my Events page for more upcoming dates and topics!
Unfortunately, I had to cancel this talk (originally scheduled on June 13th) due to illness, but I’m pleased that I have been able to reschedule it to July 4th!
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, July 4th, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
- Why does stress matter?
- Tips for sound sleep
- The importance of exercise to bust stress
See my Events page for more upcoming dates and topics!
Stress management talk June 20th
15/Jun/12 06:30 AM
by Kate Whimster, BCom, MIFHI, ND
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, June 20th, 7pm at the Deer Park Library (40 St. Clair Avenue East, Toronto). Call the library at 416-393-7657 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
See my Events page for more upcoming dates and topics!
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, June 20th, 7pm at the Deer Park Library (40 St. Clair Avenue East, Toronto). Call the library at 416-393-7657 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
- Why does stress matter?
- Tips for sound sleep
- The importance of exercise to bust stress
See my Events page for more upcoming dates and topics!
Stress management talk June 13th
10/Jun/12 04:30 PM
by Kate Whimster, BCom, MIFHI, ND
CANCELLED DUE TO ILLNESS
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, June 13th, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
See my Events page for more upcoming dates and topics!
CANCELLED DUE TO ILLNESS
I will be giving a free talk as part of my 4 Seasons of Wellness program called Summer: Stress Management on Wednesday, June 13th, 7pm at the Main Street Library (137 Main Street, Toronto). Call the library at 416-393-7700 to RSVP!
It’s at the root of all disease and you have the power to change it. Get a handle on stress and learn some simple and effective stress management techniques.
Topics will include:
- Why does stress matter?
- Tips for sound sleep
- The importance of exercise to bust stress
See my Events page for more upcoming dates and topics!
My favourite things in personal care 2012
02/Feb/12 04:18 PM
by Kate Whimster, BCom, MIFHI, ND
For several years I’ve considered writing a “favourite things” blog (a la Oprah’s favourite things). These are all things I use myself (as evidenced by the photos of this stuff in my house!) and LOVE (not just like). This is NOT an endorsement or advertisement and I’m not getting paid by anyone to put a product in this blog.
Dr. Hauschka lip care stick
This is the “favourite thing” that inspired this whole blog! Dr. Hauschka’s Lip Care Stick is by far the most expensive lip balm I’ve ever bought but it is well worth it! From the first time a co-worker at Peaches and Green recommended it, I have not looked back. It is so superior to every other lip balm I’ve tried that I have (at time of writing) 6 tubes of it in my home. These tubes are in various stages of use, from brand new to “digging out the last little bit” stage:
Meditation as Medicine book
Meditation as Medicine by Dharma Singh Khalsa is a book I recommend to anyone interested in starting a meditation practice as well as anyone who wants to learn more about specific meditations for different healthy concerns. The author is an anesthesiologist who shares many different meditations for beginners and lists meditation treatments for a lot of medical concerns complete with diagrams and great step-by-step instruction.
David’s Tea
Last fall I did a brief stint working part-time at David’s Tea and while I am too busy to continue there, I do LOVE their products! Tea can be so fun and healthy, so why not enjoy this treat rather than high-calorie coffee drinks or junk food? My top 3 favourite teas are Vanilla Oolong, Secret Weapon (a white tea), and Jessie’s Tea (caffeine-free rooibos tea). I also highly recommend the perfect mug (I have a glass one at work and a ceramic one at home) - it truly is perfect for making a wonderful cup of tea!
Urban Spa silk eye pillow
I like to sleep in complete darkness, and by complete I mean no light through the window or from electronics (which is why my phone is in another room and I cover my clock). To help achieve this total darkness, I NEED my Urban Spa Silk Eye Pillow! I have tried many eye masks over the years, but I always come back to this one because it is so wonderful. It blocks light really well, it is soft on my face, it is adjustable (which is important as the elastic stretches out over time), and it smells of soothing lavender!
Derma E microdermabrasion scrub
I have very fair, delicate skin and I find that any breakout leaves pigment and too much sun exposure leaves sun spots. One of the products I find really helpful is Derma E Microdermabrasion Scrub. This scrub is fine and gentle and I find it helps get rid of rough skin and dark spots. I use it about once per week followed by either my Green tea face mask or Egg yolk face mask.
Pure and Natural shampoo and conditioner
We used to carry some Pure and Natural products at Peaches and Green and when I started using the Daily Moisturizing Shampoo and Daily Light Conditioner, I got several comments (sometimes for complete strangers, such as in the gym!) that my hair was looking really shiny and healthy! I really love these two products and now order them from Carina Organics in the large bottles!
For several years I’ve considered writing a “favourite things” blog (a la Oprah’s favourite things). These are all things I use myself (as evidenced by the photos of this stuff in my house!) and LOVE (not just like). This is NOT an endorsement or advertisement and I’m not getting paid by anyone to put a product in this blog.
This is the “favourite thing” that inspired this whole blog! Dr. Hauschka’s Lip Care Stick is by far the most expensive lip balm I’ve ever bought but it is well worth it! From the first time a co-worker at Peaches and Green recommended it, I have not looked back. It is so superior to every other lip balm I’ve tried that I have (at time of writing) 6 tubes of it in my home. These tubes are in various stages of use, from brand new to “digging out the last little bit” stage:
Meditation as Medicine book
Meditation as Medicine by Dharma Singh Khalsa is a book I recommend to anyone interested in starting a meditation practice as well as anyone who wants to learn more about specific meditations for different healthy concerns. The author is an anesthesiologist who shares many different meditations for beginners and lists meditation treatments for a lot of medical concerns complete with diagrams and great step-by-step instruction.
David’s Tea
Last fall I did a brief stint working part-time at David’s Tea and while I am too busy to continue there, I do LOVE their products! Tea can be so fun and healthy, so why not enjoy this treat rather than high-calorie coffee drinks or junk food? My top 3 favourite teas are Vanilla Oolong, Secret Weapon (a white tea), and Jessie’s Tea (caffeine-free rooibos tea). I also highly recommend the perfect mug (I have a glass one at work and a ceramic one at home) - it truly is perfect for making a wonderful cup of tea!
Urban Spa silk eye pillow
I like to sleep in complete darkness, and by complete I mean no light through the window or from electronics (which is why my phone is in another room and I cover my clock). To help achieve this total darkness, I NEED my Urban Spa Silk Eye Pillow! I have tried many eye masks over the years, but I always come back to this one because it is so wonderful. It blocks light really well, it is soft on my face, it is adjustable (which is important as the elastic stretches out over time), and it smells of soothing lavender!
Derma E microdermabrasion scrub
I have very fair, delicate skin and I find that any breakout leaves pigment and too much sun exposure leaves sun spots. One of the products I find really helpful is Derma E Microdermabrasion Scrub. This scrub is fine and gentle and I find it helps get rid of rough skin and dark spots. I use it about once per week followed by either my Green tea face mask or Egg yolk face mask.
Pure and Natural shampoo and conditioner
We used to carry some Pure and Natural products at Peaches and Green and when I started using the Daily Moisturizing Shampoo and Daily Light Conditioner, I got several comments (sometimes for complete strangers, such as in the gym!) that my hair was looking really shiny and healthy! I really love these two products and now order them from Carina Organics in the large bottles!
The secrets of sleep
28/Jun/10 11:23 AM
Fascinating National Geographic article about sleep. Also, check out my previous blog on Sleep and Metabolic Syndrome.
Is lack of sleep making you fat?
24/Nov/09 10:56 AM
by Kate Whimster, BCom, MIFHI, ND
I wrote a research paper looking the relationship between sleep duration and metabolic syndrome and this blog is a summary of what I learned. References are listed at the end and can be found on PubMed.
Metabolic syndrome is a group of metabolic risk factors used to identify individuals at risk for cardiovascular disease (1). A correlation between sleep duration and the development of metabolic syndrome has been observed.
The National Cholesterol Education Program (NCEP) Adult Treatment Panel III diagnosis of metabolic syndrome requires the presence of three or more of the following features (1):
1. Waist circumference:
- Men: Greater than or equal to 102cm (40in)
- Women: Greater than or equal to 88cm (35in)
2. Triglycerides: Greater than or equal to 1.7mmol/L (150 mg/dL)
3. HDL cholesterol:
- Men: Less than 1.0mmol/L (40mg/dL)
- Women: Less than 1.3mmol/L (50mg/dL)
4. Blood pressure: Greater than or equal to 130/85 mmHg or medicated for hypertension
5. Fasting blood glucose: Greater than or equal to 5.6mmol/L (100mg/dL) or medicated for hyperglycemia
First-line treatment focuses on lifestyle factors such as dietary modification and increased physical activity (1). However, given that “‘normal’ average sleep duration has decreased from about 9 h per night in 1910 to about 7.5 h currently, (2)” and mounting evidence that sleep deprivation causes physiological changes that lead to metabolic syndrome, sleep deprivation is another important lifestyle factor to consider.
Short sleep duration (less than 6 hours per night) is associated with the highest risk for metabolic syndrome, but long sleep duration (more than 8 or 9 hours per night) is also associated with increased risk. The lowest risk was seen in subjects sleeping 7-8 hours per night (3,4).
With regards to abdominal obesity, “very short and short sleepers were at least 1.6 times more likely to meet criteria for abdominal obesity … compared with individuals who slept 7 to 8 hours per night (4).”
There is also a correlation between insulin resistance and sleep duration, both short and long: “with the reference group, the odds of meeting the glucose criterion were at least 1.7 times greater in the very short (< 6 hours) and long (> 8 hours) sleeper groups (4).” It is also likely that insulin resistance due to altered metabolism resulting from inadequate sleep develops gradually over years. One study restricted sleep in healthy young men to four hours per night for six nights and found that sleep debt led to impaired carbohydrate tolerance. Decreased morning insulin sensitivity was observed after 6 days of sleep restriction compared to when subjects were fully rested (6). “These results suggest that insulin sensitivity was lower on the 6th than on the 5th day of sleep restriction and thus that insulin resistance may develop progressively with increasing exposure to partial sleep loss (5).”
The Sleep Heart Health Study found that sleep duration was associated with risk of hypertension, with those sleeping less than 6 and 6-7 hours and those sleeping 8-9 and 9 or more hours demonstrating increased risk (6). A longitudinal analyses of the first National Health and Nutrition Examination Survey demonstrated that sleep durations of “< or =5 hours per night were associated with a significantly increased risk of hypertension … in subjects between the ages of 32 and 59 years (7).”
The studies discussed above have also found a relationship between increased sleep and metabolic syndrome. When examined more closely in one study, relationships between long sleep duration and metabolic syndrome and elevated glucose “were no longer significant with adjustment for use of antihypertensive medication, which has been shown to impact fasting blood glucose levels (4).” There is also a relationship between long sleep duration and sleep apnea, suggesting that “long sleep duration is a proxy for sleep disordered breathing and that sleep apnea drives the relationship between long sleep duration and health outcomes (4).”
Sleep quality is also an important factor to consider. An observational, cross-sectional study demonstrated that “poor global sleep-quality scores on the Pittsburgh Sleep Quality Index were related significantly to the presence of the metabolic syndrome (8).”
Studies relating sleep duration to metabolic changes are often confounded by pre-existing conditions (such as diabetes or hypertension), lifestyle habits (such as smoking, diet, alcohol intake, and caffeine intake), and other factors affecting sleep (such as sleep apnea). It is therefore important that studies of sleep duration take these factors into account and control for them as much as possible in order to establish a clear relationship between sleep and health outcomes. One researcher has challenged the above conclusions by offering three criticisms. First, “few obese adults/children are short sleepers, and few short sleeping adults/children are obese or suffer obesity-related disorders (9).” Second, the clinical risk only emerges from very short or long sleep duration and develops over many years, so while acute sleep restriction does lead to leads to glucose intolerance and metabolic syndrome “this is too little sleep and cannot be sustained beyond a few days (9).” Finally, he offers an alternative explanation for the relationship between sleep and metabolism: “habitually insufficient sleep could contribute towards obesity, metabolic syndrome, etc., via sleepiness-related inactivity and excess energy intake (9).”
It seems obvious that sleep is an important factor in health, but it is often overlooked by both conventional and naturopathic practitioners. Based on the studies discussed, the optimal sleep duration is between 7-8 hours per night. Many patients fail to prioritize sleep or have trouble falling asleep easily, both issues that can be greatly aided by naturopathic interventions. Sleep quality is also an important consideration and naturopathic doctors are also well equipped to make recommendations in this area.
1. MD Consult. Metabolic Syndrome. Accessed 18 Nov 2008. Available at: http://www.mdconsult.com.
2. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999 Oct 23;354(9188):1435-9.
3. Choi KM, Lee JS, Park HS, Baik SH, Choi DS, Kim SM. Relationship between sleep duration and the metabolic syndrome: Korean National Health and Nutrition Survey 2001. Int J Obes (Lond). 2008 Jul;32(7):1091-7. Epub 2008 May 13.
4. Hall MH, Muldoon MF, Jennings JR, Buysse DJ, Flory JD, Manuck SB. Self-reported sleep duration is associated with the metabolic syndrome in midlife adults. Sleep. 2008 May 1;31(5):635-43.
5. Knutson KL, Spiegel K, Penev P, Van Cauter E. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78. Epub 2007 Apr 17. Review.
6. Gottlieb DJ, Redline S, Nieto FJ, Baldwin CM, Newman AB, Resnick HE, Punjabi NM. Association of usual sleep duration with hypertension: the Sleep Heart Health Study. Sleep. 2006 Aug 1;29(8):1009-14.
7. Gangwisch JE, Heymsfield SB, Boden-Albala B, Buijs RM, Kreier F, Pickering TG, Rundle AG, Zammit GK, Malaspina D. Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey. Hypertension. 2006 May;47(5):833-9. Epub 2006 Apr 3.
8. Jennings JR, Muldoon MF, Hall M, Buysse DJ, Manuck SB. Self-reported sleep quality is associated with the metabolic syndrome. Sleep. 2007 Feb 1;30(2):219-23.
9. Horne JA. Short sleep is a questionable risk factor for obesity and related disorders: statistical versus clinical significance. Biol Psychol 2008;77:266-76.
I wrote a research paper looking the relationship between sleep duration and metabolic syndrome and this blog is a summary of what I learned. References are listed at the end and can be found on PubMed.
Metabolic syndrome is a group of metabolic risk factors used to identify individuals at risk for cardiovascular disease (1). A correlation between sleep duration and the development of metabolic syndrome has been observed.
The National Cholesterol Education Program (NCEP) Adult Treatment Panel III diagnosis of metabolic syndrome requires the presence of three or more of the following features (1):
1. Waist circumference:
- Men: Greater than or equal to 102cm (40in)
- Women: Greater than or equal to 88cm (35in)
2. Triglycerides: Greater than or equal to 1.7mmol/L (150 mg/dL)
3. HDL cholesterol:
- Men: Less than 1.0mmol/L (40mg/dL)
- Women: Less than 1.3mmol/L (50mg/dL)
4. Blood pressure: Greater than or equal to 130/85 mmHg or medicated for hypertension
5. Fasting blood glucose: Greater than or equal to 5.6mmol/L (100mg/dL) or medicated for hyperglycemia
First-line treatment focuses on lifestyle factors such as dietary modification and increased physical activity (1). However, given that “‘normal’ average sleep duration has decreased from about 9 h per night in 1910 to about 7.5 h currently, (2)” and mounting evidence that sleep deprivation causes physiological changes that lead to metabolic syndrome, sleep deprivation is another important lifestyle factor to consider.
Short sleep duration (less than 6 hours per night) is associated with the highest risk for metabolic syndrome, but long sleep duration (more than 8 or 9 hours per night) is also associated with increased risk. The lowest risk was seen in subjects sleeping 7-8 hours per night (3,4).
With regards to abdominal obesity, “very short and short sleepers were at least 1.6 times more likely to meet criteria for abdominal obesity … compared with individuals who slept 7 to 8 hours per night (4).”
There is also a correlation between insulin resistance and sleep duration, both short and long: “with the reference group, the odds of meeting the glucose criterion were at least 1.7 times greater in the very short (< 6 hours) and long (> 8 hours) sleeper groups (4).” It is also likely that insulin resistance due to altered metabolism resulting from inadequate sleep develops gradually over years. One study restricted sleep in healthy young men to four hours per night for six nights and found that sleep debt led to impaired carbohydrate tolerance. Decreased morning insulin sensitivity was observed after 6 days of sleep restriction compared to when subjects were fully rested (6). “These results suggest that insulin sensitivity was lower on the 6th than on the 5th day of sleep restriction and thus that insulin resistance may develop progressively with increasing exposure to partial sleep loss (5).”
The Sleep Heart Health Study found that sleep duration was associated with risk of hypertension, with those sleeping less than 6 and 6-7 hours and those sleeping 8-9 and 9 or more hours demonstrating increased risk (6). A longitudinal analyses of the first National Health and Nutrition Examination Survey demonstrated that sleep durations of “< or =5 hours per night were associated with a significantly increased risk of hypertension … in subjects between the ages of 32 and 59 years (7).”
The studies discussed above have also found a relationship between increased sleep and metabolic syndrome. When examined more closely in one study, relationships between long sleep duration and metabolic syndrome and elevated glucose “were no longer significant with adjustment for use of antihypertensive medication, which has been shown to impact fasting blood glucose levels (4).” There is also a relationship between long sleep duration and sleep apnea, suggesting that “long sleep duration is a proxy for sleep disordered breathing and that sleep apnea drives the relationship between long sleep duration and health outcomes (4).”
Sleep quality is also an important factor to consider. An observational, cross-sectional study demonstrated that “poor global sleep-quality scores on the Pittsburgh Sleep Quality Index were related significantly to the presence of the metabolic syndrome (8).”
Studies relating sleep duration to metabolic changes are often confounded by pre-existing conditions (such as diabetes or hypertension), lifestyle habits (such as smoking, diet, alcohol intake, and caffeine intake), and other factors affecting sleep (such as sleep apnea). It is therefore important that studies of sleep duration take these factors into account and control for them as much as possible in order to establish a clear relationship between sleep and health outcomes. One researcher has challenged the above conclusions by offering three criticisms. First, “few obese adults/children are short sleepers, and few short sleeping adults/children are obese or suffer obesity-related disorders (9).” Second, the clinical risk only emerges from very short or long sleep duration and develops over many years, so while acute sleep restriction does lead to leads to glucose intolerance and metabolic syndrome “this is too little sleep and cannot be sustained beyond a few days (9).” Finally, he offers an alternative explanation for the relationship between sleep and metabolism: “habitually insufficient sleep could contribute towards obesity, metabolic syndrome, etc., via sleepiness-related inactivity and excess energy intake (9).”
It seems obvious that sleep is an important factor in health, but it is often overlooked by both conventional and naturopathic practitioners. Based on the studies discussed, the optimal sleep duration is between 7-8 hours per night. Many patients fail to prioritize sleep or have trouble falling asleep easily, both issues that can be greatly aided by naturopathic interventions. Sleep quality is also an important consideration and naturopathic doctors are also well equipped to make recommendations in this area.
1. MD Consult. Metabolic Syndrome. Accessed 18 Nov 2008. Available at: http://www.mdconsult.com.
2. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999 Oct 23;354(9188):1435-9.
3. Choi KM, Lee JS, Park HS, Baik SH, Choi DS, Kim SM. Relationship between sleep duration and the metabolic syndrome: Korean National Health and Nutrition Survey 2001. Int J Obes (Lond). 2008 Jul;32(7):1091-7. Epub 2008 May 13.
4. Hall MH, Muldoon MF, Jennings JR, Buysse DJ, Flory JD, Manuck SB. Self-reported sleep duration is associated with the metabolic syndrome in midlife adults. Sleep. 2008 May 1;31(5):635-43.
5. Knutson KL, Spiegel K, Penev P, Van Cauter E. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78. Epub 2007 Apr 17. Review.
6. Gottlieb DJ, Redline S, Nieto FJ, Baldwin CM, Newman AB, Resnick HE, Punjabi NM. Association of usual sleep duration with hypertension: the Sleep Heart Health Study. Sleep. 2006 Aug 1;29(8):1009-14.
7. Gangwisch JE, Heymsfield SB, Boden-Albala B, Buijs RM, Kreier F, Pickering TG, Rundle AG, Zammit GK, Malaspina D. Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey. Hypertension. 2006 May;47(5):833-9. Epub 2006 Apr 3.
8. Jennings JR, Muldoon MF, Hall M, Buysse DJ, Manuck SB. Self-reported sleep quality is associated with the metabolic syndrome. Sleep. 2007 Feb 1;30(2):219-23.
9. Horne JA. Short sleep is a questionable risk factor for obesity and related disorders: statistical versus clinical significance. Biol Psychol 2008;77:266-76.