You’ve heard humans need at least 8 hours of shut eye per night, but is that really so? After decades of blaming sleep deprivation for everything, researchers aren’t so sure about how many hours you need. Here’s what you should know.
Experts understand the importance of sleep to have good health. Sleeping is an essential process for mental health and it’s a time your body spends repairing and renovating itself. But where did this 8-hour-rule come from?
According to historian Craig Koslofsky, this is a rather new invention that started in the seventeenth century and got stronger with the rise of industrialization. Before workers were needed at factories very early in the morning, there are reports of people having two distinct ‘sleep periods’, with a couple hours of waking time in-between . These sleep periods lasted around 4 hours each, and were thought of as the ‘natural’ way of spending the night.
According to different studies, sleeping for 8 or 9 hours straight might actually be going against our physiology. Human sleep is broken up into distinct cycles that last between one and two hours. In-between these cycles, you have a very light sleep and can easily wake up . On top of it, as the night goes on your sleep becomes slightly less deep, which is why many people say that sleep before midnight is more restful than sleep after. Waking up in the middle of the night isn’t something to worry about: it just means your internal clock is working.
Although it’s still common to hear recommendations about sleeping 8 hours or even more, studies surrounding its actual benefits are inconclusive.
In contrast, some studies point out that the traditional ‘eight hours per night’ might do more harm than good in some cases.
For example, a huge, decade-long study on sleep published in 2002 showed sleeping 8 hours could be associated with an increased mortality risk. This study took more than 1 million subjects and followed their sleep patterns . Then, they compared their mortality rates. The results were pretty interesting: people who slept for 7 hours per night had a lower mortality rate than everyone else. Sleeping 8 to 9 hours a night was associated with a 15% hike in mortality, just like sleeping for 6 hours. Unfortunately, insomnia medication was also associated with a higher risk, although self-reported insomnia by itself didn’t heighten the risk.
Unfortunately, these results didn’t take into account comorbidities, or other diseases that appeared throughout the study. As such, researchers cannot say for sure that sleeping for 8 hours, or less than 6 hours, will inevitably lead to an earlier grave. As of the writing of this piece, there’s still room for further research to understand the exact role of sleep on long-term life expectancy.
So considering research shows 8 hours of sleep might not be the best option for you, what’s the right choice?
Some people try to stick to what their bodies would ‘naturally’ need. In contrast to what you would think, you don’t need to sleep from the moment the sun is down. In fact, a recent study from a UCLA research group shows our ancestors probably had very similar sleep patterns to yours.
Although you might think modern life has made humanity sleep deprived, reality might not be as drastic. After studying a group of contemporary hunter-gatherer societies in different locations, there seem to be some common trends.
For example, none of the studied groups went to bed at sundown. The subjects stayed up for around 4 hours and in average slept less than 7 hours every night. This is actually on the lower end of most modern people’s sleep schedules . Plus, sleep patterns changed with the seasons: they slept more in the winter and less in the summer. This is probably how our ancestors slept and means it’s in line with the human body’s needs.
All in all, sleep research is still inconclusive. Most sleep researchers now consider the 8-hour-rule a generalization that might not work for many adults. The natural rhythm for most bodies seems to fall somewhere between 6 and 7 hours of sleep per night, and considering the studies we mentioned, this actually might be better for your long-term life expectancy .
You shouldn’t stress about reaching those coveted ‘8 hours’, especially if you’re trying to do it for health. Like with most things, the best option is listening to your body and needs. If you want to try the ‘segmented sleep’ from pre-seventeenth century, taking a break in the middle of the night, or would rather go to bed later at night and only sleep six hours, go for it. Gauge how your body feels, your fatigue levels, and adjust accordingly.