We all need sleep. Some people claim that they need more, some claim they need less, but everyone needs at least a moderate amount in order to function properly. The most common amount of time that gets mentioned is about eight hours. If we calculate that with the average life expectancy (for people in the U.S.), which is about 79 years, we come to the realization that we spend a third of our life sleeping. And for most people that is an unsettling thought. But this eight-hour sleep schedule has gone through years of evolution and still stayed the same. There must be a reason for that.
And the eight hours that everyone is mentioning when talking about a healthy sleep schedule is not random. That is a number that our body naturally craves. During testing, scientists put people in a room with no natural light, and in the evening they allowed them a nine-hour period for sleep. All of the participants slept an average of eight hours, even when given an opportunity for more.
And how does sleep deprivation affect all of this? How little sleep is actually enough to get by, and not suffer any adverse effects? Scientists performed two tests where participants were deprived of sleep. At the beginning of the experiment, the scientists let participants sleep for eight hours and then let them perform cognitive tests. The tests showed how fast a person reacts, how they interpret written word, and how often they doze off, even for just a second or two. These periods of “sleep”, that last for a brief moment, are called microsleep, and they happen to everyone. When these tests were finished, the researchers had a baseline which they then used to perform further testing.
After the initial tests, the participants were divided into four groups. The first group slept for eight hours, the second had six, the third group had four, and then the last group was not allowed any sleep for a period of three days.
As expected, the last group showed what kind of catastrophic consequences sleep deprivation can have on the human body. Even one night without sleep is enough to completely throw you out of balance. Being deprived of sleep for one day has almost the same effect as being legally drunk. The other groups, except for the one that slept eight hours, had similar side effects. Their cognitive performance after ten days of limited sleep was almost identical to the group that had zero hours of sleep. So basically, less than one hour of sleep deprivation is enough for someone to become cognitively impaired.
If you deprive yourself for one hour a day, every day, you will see a constant decline in cognitive functioning. Something similar to this can be felt during the daylight savings time switch. And when people claim they have too much to do, and that is the reason they sleep only five hours, there is a good chance that those five hours of sleep are to blame. They sleep five hours, drastically reduce their cognitive functionality and because of that, they accomplish less.