Scientists led by Derk-Jan Dijk studied 110 healthy volunteers who did not have any sleep disorders and did not complain of lack of sleep. By subjecting them to various fluctuations in the periods of sleep and wakefulness, under different conditions, they evaluated the degree of drowsiness that the subjects exhibited as a result of such exposure.
During the first night of the experiment, when the volunteers remained in bed for 8 hours, the average sleep duration was:
7,23 hours (20-30 years old);
6,83 hours (40-55 years old);
6,51 hours (66-83 years).
The oldest group slept 20 minutes less than the average and 43 minutes less than the youngest. It has also been shown to shorten the duration of the phases of slow wave sleep.
Sleepiness during waking periods was tested by inviting volunteers to take another nap. As you know, daytime sleep is a natural and extremely useful thing, unfortunately, rarely available to modern people. The volunteers were given such an opportunity. The rate of falling asleep showed a relationship with age.
20-30-year-olds were “cut off”, on average, in 8,7 minutes;
40-55-year-olds – 11,7;
66-83 year olds – in 14,2 minutes.
This finding is in complete agreement with a 2008 study in which volunteers were forced to stay in bed in the dark for 16 hours a day. Then it was shown that young people slept on average 9 hours, while the elderly – only 7,5. At the same time, scientists admit that there is no sufficiently accurate knowledge about the mechanisms and functions of sleep, and it is still impossible to say with complete certainty how much sleep a particular person needs.
By LiveScience publication
See also: 6 Ways to Improve Sleep