How much sleep is enough? This question is not easy to answer, and is very subjective. Some think they need at least seven hours, some say ten. In fact this varies from person to person and also with age. It has been shown that babies sleep nearly all day. As they get older, they need less and less sleep. It is well known that the older we are, the less sleep we need. One of the common complaints of the elderly is that they cannot sleep. They hate to be awake and alone at night. They take sleeping pills, as they feel distressed when they cannot sleep.
How much sleep is required to restore, to repair, to recuperate, so that the next day we feel refreshed and satisfied?
There have been several studies of sleep deprivation. In 1959, Peter Tripp, who worked at a US radio station, went without sleep for 200 hours or 8.33 days to raise money for charity. After five days without sleep he had hallucinations and began to see things. He reported seeing flames pouring out from a drawer and worms crawling all over the doctor’s coat. He continued to do his broadcast in the daytime, but at night he was forced to stay awake. Eventually, after 200 hours, he stopped the ordeal and went to sleep. As he had not been sleeping for over eight days, he was expected to sleep for at least a couple of days, but though free to sleep for as long as he wanted, he slept continuously for only 13 hours, then woke up and felt refreshed. He was back to himself after that, although he felt depressed for a few months afterwards. Another well-known case was that of Randy Gardner. In 1964,as a 17 year old student, he decided to break a record of 260 hours without sleep for his science project. He stayed awake with the help of his friends, engaging in mental and physical activities. He did not take any drugs or stimulants. He felt extremely tired, his eyelids were heavy and burning, but he did not have any hallucinations. He managed to break the record, and stayed awake for a total of 264 hours or 11 days. He appeared to be quite well, even up to the last minute of the ordeal, and thought that he would be able to continue to do without sleep for a longer period if he wanted to. After a sleep deprivation of 264 hours, he fell asleep once he was in bed. Again, he was free to sleep as much as he wanted, but he slept a straight IS hours only. This sleep was monitored in the sleep laboratory of the San Diego Naval Hospital. After waking up, he felt well and had no after-effects.
In Edinburgh, Ian Oswald reported in 1966 the case of six medical students who went into sleep deprivation for 108 hours or 4.5 days. When the experiment was terminated, and they finally went to sleep, they slept for an average of 12 to 14 hours straight.
The following is a summary of the three reports of sleep deprivation:
Tripp 200 hours (8.33 days) without sleep—slept 13 hours
Gardner 264 hours (11.0 days) without sleep—slept 15 hours
Oswald’s students 108 hours (4.5 days) without sleep—slept 13 hours
The above studies appear to contradict what we normally estimate as the amount of sleep required. If we normally sleep 7 hours each 24 hours, then Tripp who did not sleep for 8.33 days would need 58.31 hours sleep to catch up; Gardner who did not sleep for 11 days would need 77.00 hours to recuperate; and the Oswald’s students who did not sleep for 4.5 days would need 31.50 hours sleep.
If we work out the average amount of sleep per day that these subjects had, we find that they needed only about 2 hours sleep every 24 hours:
Tripp Slept 13 hours after 8.33 days = 1.56 hours/day
Gardner Slept 15 hours after 11 days – 1.36 hours/day
Oswald’s students Slept 13 hours after 4.5 days – 2.89 hours/day
Does this imply that we need only a minimum of two to three hours sleep each day, and the rest of the time that we spend sleeping is a waste or a luxury? Of course not; we must remember that during sleep deprivation these subjects were not functioning well. Tripp was hallucinating, Gardner had heavy and tired eyes, and Oswald’s students were not enjoying the experience one bit. Hence two to three hours sleep each day is not sufficient for normal healthy functioning.
However, we can draw a few important conclusions from the above sleep deprivation reports.
* After a few sleepless nights, we do not need the same number of hours sleep that we had missed out on to recuperate. A few hours more than the normal sleep period is sufficient to feel refreshed and well again. In other words, we do not need to pay back the sleep debt we create with an equal amount of sleep.
* The duration of the sleep deprivation is not directly proportional to the number of hours spent in sleep after the ordeal. In fact, in all three reports about 13 to 15 hours was required, although Gardner had been awake twice as long as the students.
* Even when these volunteers were extremely sleepy, they could not stay asleep for more than 15 hours. There appears to be a limit to how long we can continuously sleep without waking up. Is there a waking centre in the brain?
* There is no report of serious ill-health or death arising from not sleeping. Our bodies seem to be able to withstand continuous insomnia quite well.
Nowadays it is thought that Tripp, Gardner, and Oswald’s students did not stay awake continuously during all those days of sleep deprivation. If their brain waves had been recorded continuously, there may have been records of very brief periods of sleep. Momentary sleep whilst the person is apparently still awake is called ‘microsleep’. Microsleep lasts for just a few seconds, but is very refreshing.
Microsleep occurs in less fit people, especially in the elderly. Physical activities tend to reduce the frequency of microsleep. It is well known that when we are older we need less sleep; most elderly people sleep only a few hours each day. Because the elderly have fewer physical activities in the day and are less fit, they lapse into microsleep very frequently during the day. It has been postulated that this is one of the reasons why the elderly do not require that much sleep at night.
From the above, we see that the minimum number of hours of sleep can be as little as two hours a day for a short period. We also know that there are no reports of death from insomnia, although there are millions of reports of people who have died from an overdose of the drugs that treat insomnia. So why panic when you cannot sleep for a few hours at night?
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