Can we adapt to less sleep?

If we are given an opportunity most of us can eat and drink more than our true physiological needs and even cut down food and water intake by 15 – 20 per cent without any harmful effects. In the case of food limitation, body weight will fall a little and then stabilize at a new weight. Definitely time is required for adaptation and there will be some hunger at first, but there would not be starvation, provided the food restriction is not too great. 

In young adults the average sleep length is about the 7.5 hours with a standard deviation of about one hour. That’s around 65% of young adults sleep between 6.5 and 8.5 hours and about 95% between 5.5 and 9.5 hours. We have good evidence that, a normal sleeper can reduce the average 7.5 hours sleep time to 1.5-2 hours, on a more or less permanent basis, without having excessive daytime sleepiness or impaired psychological performance. Majority of us could go down to 3 hours sleep a night. 

The rule is obvious: the greater the sleep reduction, the more is the difficulty in adapting. We can even manage without any sleep for one night. Not only can we take less sleep, but it is very easy to sleep longer than normal.