Can we function on less than the “required” 8 hours of sleep? Can we actually train our bodies to require less sleep?
Sleep experts say no, but anecdotal evidence says yes.
In college I once put myself through a strict sleep schedule. I needed a couple more hours in the day to get work done, so I decided to restrict myself to 6 hours a night. That doesn’t seem so bad, but I didn’t allow myself to catch up on the weekends. Day after day of restricted sleep begins to add up, and with no sleeping in on the weekends, my energy started to take a toll.
Interestingly, however, things started to “click” after a week or two. Maybe I didn’t feel my best, but I started to wake up just fine, sometimes even before the alarm. I enjoyed my 18-hour days for the rest of the semester, but once I went on vacation I reverted to 8-10 hour sleeps, laziness, etc.
Since then I’ve been convinced that our bodies are capable of adapting to restricted sleep schedules.
But what do the sleep experts have to say?
The Harvard Medical School Guide to a Good Night Sleep says this:
Unfortunately, there’s no way to train the body to reduce its sleep need. Studies on chronic partial sleep deprivation, restricting people to only four or five hours of sleep for several weeks, found that people continue to get sleepier and their performance becomes more impaired the longer the study goes on. There is no plateau or limit to how sleepy and impaired they get. To meet a job deadline or study for a final exam you may be able to function on less sleep, but you will feel more tired, work less efficiently, and get less done.
The main problem I see with the above quote is that they referenced chronic sleep deprivation studies — sleep studies where subjects were restricted to 5 hours or less per night!
Very few sleep studies have measured the effects of gradual or partial sleep restriction. After all, what study will get you more funding and a bigger headline? Probably a study on chronic sleep restriction — might as well scare people into more sleep so they can pour money into the billion-dollar sleeping pill business.
I did find one sleep study that suggests “sleep training” is possible, but…
Before we go on, I need to clarify between two different types of “sleep training”. First, our sleep need is largely determined by lifestyle factors. If you eat whole foods, go to the gym, and are psychologically motivated, you will naturally need less sleep than someone who eats junky processed foods, watches TV all day, and is unmotivated.
Some people notice that by shifting to a healthier lifestyle (e.g. diet changes) they suddenly need less sleep.
That’s good, but let’s leave that for another article.
My interest for this article is: Is it possible to need less sleep simply by reducing the amount of sleep we get? That is, can we train our bodies to adapt to less sleep?
One older study published in the journal Psychophysiology suggests that we can adapt to restricted sleep.
The study monitored six 8-hour sleepers for more than one year. All six subjects started off with their usual 8 hours of sleep, but then reduced to 7.5 a night for a few weeks. Then to 7.0 for a few weeks. Then to 6.5, etc. Through this gradual reduction, two subjects reached the 5.5-hour mark, two reduced to 5.0, and the last two reduced to 4.5 (yikes). Throughout this entire process, all subjects kept their wake-up times consistent, something very important in optimizing sleep quality.
So how did the subjects do?
- As sleep was reduced, time spent in light sleep was also reduced
- Time spent in deep sleep (stage 3 and stage 4) increased despite the decrease in total sleep time (!).
- Time spent in REM reduced significantly.
That’s interesting, right? Well, here’s the kicker:
After this sleep study ended, and subjects were allowed to sleep as much as they wanted, all subjects slept 1-2 hours less than their pre-study baseline! That is, these 8-hours sleepers naturally reverted to 6 to 7 hours of sleep per night instead of 8.
Our finding that 6 of our subjects continued to sleep below baseline levels a year after the end of regulated sleep was of particular interest… These data, along with the similar results from the 2 subjects studied by Johnson and MacLeod (1973), suggest that gradual sleep reduction may be an effective way to reduce [total sleep time] by 1 to 2 hrs and may permanently alter sleep habits or requirements.
Be warned, however, because below the 5.5 mark subjects reported “severe fatigue and reduced efficiency”.
Here’s something else I found interesting from the study: “Subjects reported that it often took 7 to 10 days to adapt to new reduced sleep levels.” So every time they reduced sleep by 30 minutes it took a week or two for things to “click” — hmm, sound familiar?
I you want to try out a “sleep restriction diet”, keep the following in mind:
- Sleep restriction is easier when your sleep quality is already very good.
- It might take 7 to 10 days of tiredness for your new schedule to “click” — that is, no sleeping in on weekends, keep it consistent.
- Try to reduce sleep 30 minutes at a time. So if you sleep 8 hours, go for 7.5 for a couple weeks, then 7.0.
- Most sleep studies show that continually sleeping below 6 hours will cause severe fatigue, don’t get too ambitious.
- Aim for 1 hour reduction if you’re an 8-hour sleeper. Use positive changes in diet and lifestyle to help push past that. Don’t underestimate the benefit of 1 extra hour each day. That’s over nine extra 40-hour work weeks per year.