Is too much sleep harmful? After reading this question, many residents of modern megacities will only sigh to themselves — “People have problems … But I would like to get enough sleep at least once, I would probably sleep for a week.” But it’s not about making up for the lack of sleep, but about the constant “oversleeping”. Which some scientists talk about as a harmful, and even dangerous phenomenon. Whether so it, finds out MedAboutMe.
Normal sleep duration
This is one of those issues on which the opinions of scientists are very different. Various opinions are presented in the scientific literature, and each comes with a bundle of quite convincing evidence.
The most common opinion is that the norm for a healthy adult is a daily (or rather, nightly) sleep of 7–8 hours. And less than 7 hours of sleep is harmful, since the lack of night sleep leads to disruption of circadian rhythms, metabolic processes, imbalance in the ratio of the hormones of hunger and satiety — ghrelin and leptin, the development of insulin resistance and, in the long term, type 2 diabetes mellitus, obesity, atherosclerosis, etc. And all this has really convincing, scientifically reliable evidence obtained by many scientists from different countries.
There is also plenty of evidence that “night vigils” followed by sleeping during daylight hours have a negative impact on health. This is due to a violation of the production of melatonin, which can be synthesized in the pineal gland only in the dark during sleep. This substance regulates circadian rhythms, blood pressure, affects blood sugar levels. Melatonin also inhibits the growth of melanoma tumor cells.
In 2008, Israeli scientists published an article on the results of a 10-year study, the result of which shows that women who sleep even in dim light are 22% more susceptible to breast cancer. Scandinavian scientists also found a higher susceptibility to this type of cancer, examining nurses who work on shift schedules and because of this often sleep in the daytime after night shifts.
Sleep “at the wrong time” also affects the production of cortisol, the stress hormone. Normally, this hormone is produced in the light, during wakefulness, providing the body with a higher level of activity and energy, and at night during sleep, its level decreases. If you sleep at random, these processes go astray. Elevated levels of cortisol increase the body’s susceptibility to various diseases and inflammation, increase cell resistance to insulin, which increases the risk of developing type 2 diabetes.
It would seem that with the lack of night sleep, everything is clear. But not all scientists agree with this. There are those who claim that it is natural for a person to just sleep “in several steps”, for 2–4 hours. However, convincing evidence of this theory has not yet been presented.
Sleep more than 8 hours
In recent years, there have been reports that long sleep is no less harmful than lack of sleep. Because a significant association has been found between sleeping more than 9 hours and a higher rate of death from cardiovascular disease. “The trouble came from where they didn’t expect,” that’s what they call it, right? And little sleep is harmful, and now it’s scary to oversleep?
But here’s what the experts have to say about it.
Elizabeth Clerman, Neurologist-Somnologist
We have doubts about the correctness of the conclusions made on the basis of the identified association between prolonged sleep and the risk of developing cardiovascular diseases. The fact is that the relationship can be reversed: it is not prolonged sleep that causes diseases, but a person sleeps more because he is unhealthy. Which brings us to the old “chicken or egg” problem with no solution.
In addition, many studies do not take into account factors that existed before the start of the experiment: for example, the participants’ long-term lack of sleep, their use of various medications that can affect sleep and its duration, alcohol or other psychoactive substances.
We think that sleep by itself, even longer than usual, cannot harm the body. But if there are causes that cause drowsiness, then the doctor’s attention should be paid more to them than to the actual duration of sleep, which can only be a symptom.
A group of scientists, which included Dr. Elizabeth Clerman, conducted an experiment with healthy young people who were asked to sleep “as much as they like.” After a slightly longer night’s sleep (sometimes even more than 12 hours) for the first few days, all participants soon developed a natural sleep duration of about 8.5 hours. They simply could not sleep anymore and did not want to. And if they fell asleep again, then the state of health worsened: there was a feeling of weakness, a headache. True, these phenomena quickly passed after the return to normal daytime activities.
William Scott Killgore, psychologist, psychiatrist
There are people in the human population for whom longer sleep is a natural need of the body. Among men, such “long-sleeping” about 2%, among women — about 5%. For everyone else, 7–9 hours of sleep is enough, and for teenagers — more, for older people — less. Children sleep the most, and this is completely natural, because in a dream they process the information received during wakefulness, which babies learn in large quantities.
Indeed, there are statistics showing that the life expectancy of “long-sleepers” is somewhat lower on average. But the reasons for this have not yet been identified, in any case, there are no reliable, convincing explanations for this phenomenon.
Perhaps the duration of sleep may be affected by stress or depression. In my practice, there were cases when the need for longer sleep was associated with stressful pressure, oppression of problems that a person did not want or could not solve. The dream was for him a way to “escape from reality”, to “hide low”. This is also a fairly natural reaction of the body to stress, although people are more likely to have another form of response, usually expressed in the formula “fight or flight.”
Anxiety can be caused by a situation when a person suddenly began to need more sleep, this can really indicate certain violations. If a man or woman has always slept more than others, then perhaps they simply belong to the “long sleepers”.
How to get enough sleep at night?
Since most of today’s people still do not have enough sleep, the main problem is seen in getting a good night’s sleep for the usual 7–8 hours.
Here’s what you need for this:
- Do not dine too late and too much, avoid tonic drinks in the evening.
- Sleep in a well-ventilated room in complete darkness. It is even advisable to remove luminous alarm clocks, do not leave nightlights lit, use thick curtains that do not let in the light of the moon or street lamps.
- Put your smartphone and laptop away no later than 30 minutes before bedtime. Always turn off the computer at night if it is installed near the bed.
- Take a warm bath or warm short shower before bed.
- Organize yourself a comfortable bed with a good mattress, the right pillow and the most appropriate blanket. Some, for example, are much more comfortable sleeping under a heavy blanket, others prefer a light one, so you need to try.
If 7–8 hours is definitely not enough, try “two-phase sleep”: set an alarm an hour before the desired wake-up time. When he wakes you up, drink some water and lie down again for an hour. After the first phase of sound deep sleep, the second phase will be light. Some somnologists claim that this helps to get better sleep in the same amount of time.
You can read more tips in the article “How to organize a sound and healthy sleep.”