Over the past decade, there has been increasing emphasis placed on good quality sleep as part of an excellent health regimen. Some studies have suggested that 7–8 hours of good quality sleep per night is as good for the body as not smoking. With the increasing stresses and pressures of the modern world, along with the ubiquitous presence of electronics, the quality and length of sleep is being constantly eroded.
On top of this is the very common diagnosis of sleep apnoea and some other less common but still very disturbing conditions of sleep that can markedly affect the quality and quantity of a good sleep habit.
3 recent studies on sleep have prompted me to revisit this issue. The first study published in Nature Genetics from Holland assessed the DNA and sleep characteristics in 1.3 million people who were part of the US based “23 and me” genetic screening program. It has been estimated that around 30% of the population suffer some degree of insomnia where 1 in 10 people have chronic poor sleep and subsequent daytime consequences. It has been estimated that 770 million people worldwide suffer significant chronic insomnia.
Interestingly, this new study showed that there are just under 1000 gene variants which contribute to insomnia and this appears unrelated to whether you are a lark i.e. go to bed early, wake up early or a night owl i.e. go to bed late, wake up late; which appears to be genetically determined with a 70/30 ratio of larks to night owls. But, there does appear to be a clear link between these abnormal gene variants and insomnia with depression and anxiety.
The second study published in Science Advances from the University of Rochester was performed in mice using a variety of anaesthetic regimens, one of which simulated the effects of deep non-REM sleep. This is the phase of sleep where we rejuvenate the body for the next day. Interestingly, it has been discovered that the brain has a glymphatic system. This is the part of the immune system that helps to clear waste and other toxic proteins from the brain. It appears that this system is most active during deep sleep. Thus, if we do not have good quality deep sleep, we are not clearing toxins from the brain and thus the link between poor quality sleep and the increasing risk for Alzheimer’s disease.
The final study, published in Current Biology from the University of Colorado looked at 36 healthy volunteers aged 18–40 and monitored their food intake, exposure to light and sleep over 9 nights. They split these people into 3 groups with the first group sleeping 9 hours each night for 9 nights, the second only 5 hours per night for 9 nights and the third, 5 hours per night for 5 days with an unrestricted weekend and then 2 further days of 5 hours per night. The conclusion of this study was that trying to catch up for the lost sleep on weekends does not really benefit your metabolism with anywhere between a 9–27% reduction in insulin sensitivity by this yo-yo effect on the circadian rhythm, the vital rhythm that maintains our wake-sleep cycle each day and allows the rhythmic release of a variety of body chemicals and hormones to maintain normal body balance.
The key message from all of the studies performed on sleep is that this is a vital part of your day and one that should be respected and not abused. We should be aiming for a regular, constant sleep habit that is maintained each day. With the increasing issues around all aspects of modern living, many people are cutting back on sleep or having disrupted sleep because of stress, electronics and many other factors. We hear so much about the importance of diet and exercise but it is my opinion that good quality sleep is another vital factor in the generation of good health. Sleep poorly at your peril.