If I got 6 hours of sleep, I was over the moon.Yet recent research has discovered that those who sleep less than 6 hours per night over several nights in a row trigger changes in the genes that control the immune system, sleep and wake cycles, metabolism and the body's response to stress.
The study, led by Professor Derk-Jan Dijk, director of the Surrey Sleep Research Centre at Surrey University is insightful, as you'll read below, but let's face it, we kind of already know that negative changes in the body take place when it is deprived of sleep.
We are more likely to get run down and catch colds and other viruses, we feel hungry late at night and not so hungry when we should during the day, we feel more stressed and the less sleep we get the more difficult it becomes to sleep.
The changes, which affected more than 700 genes, may shed light on the biological mechanisms that raise the risk of a host of ailments, including heart disease, diabetes, obesity, stress and depression, in those who get too little sleep.
“The surprise for us was that a relatively modest difference in sleep duration leads to these kinds of changes”, said Professor Derk-Jan Dijk, “It's an indication that sleep disruption or sleep restriction is doing more than just making you tired”.
And this is the key point here. We are all capable of struggling on, and as I have said before, the human body is very adaptable – it can tolerate a lot, but not indefinitely. At some point something gives, and that thing is your health, in one way or another.
The thinking used to be, “what's an hour here and there, I'll sleep when I'm dead”. We've all heard the bravado of those who choose a few more drinks over a few more hours sleep. But the fact is if you deprive the body of sleep for a long enough period of time you could well be sleeping dead sooner than you think.
The study took 14 men and 12 women, all healthy and aged between 23 and 31 years, and asked them to live under laboratory conditions at the Surrey Sleep Research centre for 12 days. Each volunteer visited the centre on two separate occasions.
During one visit, they spent 10 hours a night in bed for a week, and in the other, they were allowed only 6 hours in bed per night. At the end of each week, they were kept awake for a day and night, or around 39 to 41 hours.
Using EEG (electroencephalography) sensors, Professor Derk-Jan Dijk's team found that those on the 10 hours-per-night week slept around 8.5 hours a night, while those limited to 6 hours in bed each night got on average 5 hours and 42 minutes of sleep.
This is very interesting because it suggests that to get 8 hours sleep we should allow time for 9.5 hours in bed. It is worth remembering that not all the time spent in bed during the night is spent in the sleep cycle.
According to a report in the US journal Proceedings of the National Academy of Sciences, blood tests on the volunteers showed huge gene activity during sleep. The study revealed that among the sleep-deprived, the activity of 444 genes was suppressed, while 267 genes were more active than in those who slept for longer.
The study concluded that gene changes due to lack of sleep may trigger or exacerbate conditions such as obesity and diabetes, and may affect other genes such as those that govern the body's inflammatory response, which might have an impact on heart disease. Other affected genes included those linked to stress and ageing.
The study also showed that the effect on genes also altered the body clock, potentially causing a knock-on cycle of sleep disruption. “There is a feedback between what you do to your sleep and how that affects your circadian clock, and that is going to be very important in future investigations”, said Professor Dijk.
Although the study clearly proves that sleep deprivation over a prolonged period negatively impacts health, it should be noted that those who consistently get 6 hours of sleep each night and feel fine throughout the day should not worry.
This study was based on sleep deprivation and disruption, and looks at the potential effects on the body over time, not on those who have been healthily sleeping for 6 hours consistently for many years.
Having a run of bad sleep once a year isn't going to affect your health, but consistent poor sleep, of a few hours a night over a month or more, becomes problematic because it disrupts your circadian rhythms and, as the study shows, wreaks havoc with your genes.
One thing the study didn't test for was how long the volunteers' genes took to return to normal levels of activity. Although I am sure it wasn't long if the participants slept well prior to the study.