Think You Can Thrive on 4-5 Hours of Sleep? You Can’t

I’ve listened to and read about people who claim that they can get by on just a few hours (4-6) of sleep per night. Something about those claims never seemed quite right to me. I knew on those occasions when I got that kind of sleep I was kind of dragging most of the day. But maybe there are people whose mind and body can thrive on fewer hours of sleep than others.

Well as it turns out, they can’t.

It seems as if the number of hours people need is universal, and based on a recent study, the magic number is 7-8 hours of sleep each night.

Conor Wild, one of the memebr’s of the research team, explained the results.

“We found that the optimum amount of sleep to keep your brain performing at its best was between seven to eight hours every single night. That corresponds to what doctors will tell you, you need to keep your body in tip top shape as well,” Wild said.

Most intriguingly, those who exceeded the maximum suggested sleep time “were equally, as impaired as those who slept too little,” he added.

Wild also noted that “a lot of people were sleeping four hours a night on average, and that had an effect of being 8 years older in terms of their performance on some of these tests.”

The research found that reasoning and verbal abilities were most strongly impacted by too much or too little sleep, while short-term memory performance was relatively unaffected. This is different from findings in most scientific studies of complete sleep deprivation (one or two nights with little or no sleep, as opposed to chronic patterns of too little or too much sleep) and suggests that not getting enough sleep for an extended period affects your brain differently than staying up all night.

Complete sleep deprivation—that is, one or two nights with little or no sleep—did not alter reasoning or verbal skills, though it did hobble short-term memory. This finding is reassuring, given that many professionals—think of hospital residents and airline pilots—have to make life-or-death decisions based on exactly this kind of erratic sleep schedule.

So there you have it. For those of you who claim you can habitually get by on fewer hours of sleep than the rest of us, you’re just kidding yourself. And that belief could have some significant consequences when you are making important decisions. or completing critical tasks.

One thing I could not tell from the research is whether the 7-8 hours of sleep needs to be continuous, or could just getting six hours be made up for by taking a one-hour nap that same day. I’ll keep looking to see what I can find.

In the meantime, if I’m to get my 7-8 hours, it’s time for me to go to bed.

For those interested, here is the abstract from the published study:

Most people will at some point experience not getting enough sleep over a period of days, weeks, or months. However, the effects of this kind of everyday sleep restriction on high-level cognitive abilities—such as the ability to store and recall information in memory, solve problems, and communicate—remain poorly understood. In a global sample of over 10000 people, we demonstrated that cognitive performance, measured using a set of 12 well-established tests, is impaired in people who reported typically sleeping less, or more, than 7–8 hours per night—which was roughly half the sample. Crucially, performance was not impaired evenly across all cognitive domains. Typical sleep duration had no bearing on short-term memory performance, unlike reasoning and verbal skills, which were impaired by too little, or too much, sleep. In terms of overall cognition, a self-reported typical sleep duration of 4 hours per night was equivalent to aging 8 years. Also, sleeping more than usual the night before testing (closer to the optimal amount) was associated with better performance, suggesting that a single night’s sleep can benefit cognition. The relationship between sleep and cognition was invariant with respect to age, suggesting that the optimal amount of sleep is similar for all adult age groups, and that sleep-related impairments in cognition affect all ages equally. These findings have significant real-world implications, because many people, including those in positions of responsibility, operate on very little sleep and may suffer from impaired reasoning, problem-solving, and communications skills on a daily basis.

4 thoughts on “Think You Can Thrive on 4-5 Hours of Sleep? You Can’t

  1. I drag along on too little sleep. I never seem to be able to get to bed early and something always wakes me up. The few times I do push past five hours, I definitely feel better the next day!


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