I believe that lifestyle factors such as diet and exercise have potentially profound impact on health and wellbeing, and this is certainly reflected in the voluminous recommendations that come at us regarding what we should and shouldn’t be doing in these areas. However, I also take the view that another key lifestyle factor ” sleep ” does not get the attention it deserves. Most people report that they feel better in terms of energy levels when getting, say, 7 or 8 hours of sleep a night, compared to getting less 6. And on top of this there is the evidence which links short sleep duration with an increased risk of conditions such as cardiovascular disease (e.g. heart disease) and type 2 diabetes.
One such study was published in the journal Sleep Medicine . In this study, 276 individuals aged 21 to 64 were assessed for an average of 6 years each. Compared to those sleeping 7-8 hours a night, those sleeping 6 hours of less were 2.78 times more likely to develop type 2 diabetes. Of course, this does not mean that lack of sleep causes diabetes (only that these two things are associated). However, other evidence shows that inducing sleep deprivation in healthy individuals can also induce insulin resistance (a precursor of type 2 diabetes), and quickly too. This line of evidence suggests that shorter sleep duration may indeed cause type 2 diabetes through some metabolic effect.
This latest study also found that longer sleep duration was also associated with an increased risk of diabetes: individuals sleeping 9 or more hours each night, were about 2.5 times more likely to develop diabetes compared to those sleeping 7-8 hours a night. The findings from this study remained significant after other ‘confounding’ factors (such as BMI and waist circumference) were taken into account.
These findings (increased risk of diabetes with both short and long sleep), mirror the results of a previous study from the same lead author . I have previously written about this study here.
One point I made in this previous post is that, as with shorter sleep duration, we don’t know that longer sleep duration actually causes type 2 diabetes. It might be, that individuals at risk of type 2 diabetes are less healthy and need to sleep more, for instance. We’re unlikely to get much further insight regarding any causal relationship here, because it’s not very practical to make people sleep more to assess what effect this has metabolically.
I have my doubts about what relevance this has anyway, on the basis that not sleeping enough seems to be way more prevalent than sleeping ‘too much’. Plus, there is evidence that sleep duration is generally declining in industrialised countries. In a report of the study that is the focus of the blog that can be read here, I read that, fewer and fewer people sleep the optimum number of hours. A survey conducted in 1960 showed that American adults slept an average of 8 to 8.9 hours a night. By 1995, that average had dropped to 7 hours. A study conducted in 2004 by the National Center for Health Statistics found that one-third of adults aged 30 to 64 slept less than 6 hours a night.
Previously, I have also written about a study which linked short sleep duration with an increased risk of death, particularly from cardiovascular disease.
I think there’s more than enough evidence to suggest that sleep is something to be valued and protected. Yet, for whatever a multitude of reasons, sleep can easily slip down our list of priorities. Coupled with this, is the fact that there does not appear to be any political or commercial appetite for the promotion and popularisation of the potential benefits for sleep. After all, however long we sleep for, we only need to invest in one bed, and while we’re asleep we’re not contributing to the economy.
1. Chaput JP, et al. Sleep duration as a risk factor for the development of type 2 diabetes or impaired glucose tolerance: Analyses of the Quebec Family Study. Sleep Med. 2009 Mar 28. [Epub ahead of print]
2. Chaput JP, et al. Association of sleep duration with type 2 diabetes and impaired glucose tolerance. Diabetologia. 2007;50(11):2298-304.
There is also an association between lack of sleep and weight gain. People who sleep less seem to be more overweight and not necessarily because they spend those extra waking hours scoffing junk food. The link may be that less sleep interfered with production of growth hormone and excess calories go into fat rather than growth and repair.
As a personal aside I’ve never got to sleep easily and for a few years have woken during the night. Two weeks ago I got a new bed and it has transformed my sleep. I now sleep through the night and feel refreshed rather than aching when I wake up. The mattress makes all other beds feel like a hammock. I know the bed manufacturers claim that your mattress needs replacing regularly, maybe they are right
But isn’t it a personal thing? Some people feel better with less sleep and some need more. Maybe we should go by how we needed as older children and go with that. Also the quality of seep varies. Some who sleep longer may wake more often or go through the cycles in more time.
Liz, We invested in a memory foam mattress for our boy. He is happy and my wife and I both note how remarkably comfortable they are. What sort of mattress might be your recommendation?
Commenting as someone who is T2 diabetic (no pharmas) and has worked unsocial hours I think the sleep factor is important. I have recently, and with varying degrees of success, addressed issues of hyperinsulinemia. I have noted a marked improvement in the quality of my sleep and wakefulness when I have ( albeit subjectively speaking) addressed hyperinsulinemia.
I concur that sleep deprivation or restriction is disruptive to the ability to control blood sugar and by implication hormonal (insulin) balance. ‘Scoffing junk food’ seems to contribute to depleted energy levels, as does sleep deprevation, and in certain individuals depleted energy levels seems to contribute to craving more of the high GL carb rich junk food that perpetuates the feeling. At the recent ION conference Patrick Holford used the expression ’21st century-itis’. Factor in caffeine and alcohol for added disruption. Whatever the symptom, be it low energy levels, weight gain, or type 2 diabetes is the cause a common one, ie varying degree of metabolic dysfunction?
Hilda is correct to point out that people vary in how much sleep they need. Holford suggests that addressing the condition of hyperinsulinemia through adoption of a low GL diet will result in better sleep and raised energy levels. Sears suggests that a low GL diet reduces oxidative stress and will therefore confer a healthier and longer life.
I vary in how much sleep I need. I sleep more restfully, wake earlier, and feel ready for the day, when I have successfully addressed hyperinsulinemia through a low GL diet.
If I lived a lifestyle akin to my gatherer-hunter ancestors, I expect I would sleep well on any mattress.
I think people who are overweight/obese are more likely to be uncomfortable/in pain than if they were of normal weight and so they find it more difficult to fall asleep and to stay asleep, i.e. I think the weight gain causes the shorter sleep rather than being the result of the shorter sleep.
I have t2 diabetes and am now 68 years old. I do 15-20 minutes excercise four days a week at varying times of the day. A typical supper would be rutabaga with sauteed onions and tomatoes and baked salmon. I never eat any starches such as rice or potatoes or bread after 6 pm. I often, though not every evening, have one or two glasses of wine with dinner. I have also never been able to sleep more than five hours at a time, since I was a young man but recently I am lucky if I can sleep 4 or even 3 hours. I often fall asleep on the sofa for an hour or two right after breakfast. Tonight I woke up with a sweet taste in my mouth and when I tested, found my blood sugar was at 20. My normal blood sugar level was 6-7 but lately it has shot up to 8 on a regular basis but to my knowledge it has never been as high as 20 before. My question is, can lack of sleep cause my blood sugar level to go up? Or could a rise in my blood sugar be impairing my ability to sleep? Or could the wine be impairing my ability to absorb the sugar? Or could the wine be impairing my ability to sleep? I am conscientious about working on my diabetes but am confused about this.
Hi Winston, I am insulin resistant and a bordering t2. I have visited a specialist doctor recently about this problem myself. I find it hard to sleep myself and the doctor told me not to consume any wines,breads,potato or foods that will of course burn into sugar in the evenings. He said to consume them in the middle of the day and flush the system with a good quality alkaline water in the late afternoon to night before bed. He has taken me off breads and replaced it with Rye-Burgen or the Soylin type bread. Also replaced the orange sweet potato with ordinary potato’s. You are probably already eating this and made the changes if you have T2-D. Yes I would say Winston, the wine in the evenings are not agreeing with you. Hope this has been helpful and cheers for now. Glenn.
Wow! I only just saw the date above. You have probably already worked through this problem many moons ago. Lol. Glenn