Temperatures can drop significantly during winters and this can affect the human health in various ways. Many studies have discovered the effects of winter in term of an increase in the cases of cold and influenza. However, the question that has never been asked is, ‘Does the external temperature affect the sleep or the functions of sleep?’
During the winter seasons, we often notice that our sleep is interrupted and disturbed. We also experience frequent urination. Has this subject been scientifically explored? Are there any scientific explanations for these symptoms? I tried to research about this subject and found that only a few studies have been conducted on this subject. However, in this article I will try to give you a simplified picture of the impact of cold on sleep.
Now, several studies have been conducted to study the effect of cold on the sleep patterns of animals. However, none can be extrapolated to human beings, simply because humans do not live in such harsh environments.
Studies to Examine the Effect of Cold on Human Beings
Primarily, two types of studies can be conducted to examine the effects of cold on human beings. Some studies are conducted in the laboratory while others are carried out in naturally cold atmospheres, such as the Antarctic region. We will try to review the results of these studies briefly.
The studies have shown that the impact of cold weather on sleep is directly proportional to the time spent in the cold. Although the human body has a mechanism for adapting to the weather, in general, we often experience unstable sleep during colder weathers.
It has been recorded that although the cold weather does not affect the deep sleep stages (stages two and four), it reduces the REM (rapid eye movement) stage. This REM stage is vital for the brain to relax and this helps clear the mind as well as increase concentration during the day.
The reasons for the disturbed sleep are an increase in the need to urinate and the secretion of stress hormones such as adrenaline. Due to the rise in the secretion of these hormones, there is a rise in the tension and stress, and even the blood pressure, which is otherwise at its lowest level during sleep. Thus, it can be concluded that the cold weather changes the physiology of sleep. This helps us explain the rise in infections during winters.
However, it has been observed that many of these symptoms disappear when a person gets used to sleeping in the cold weather (i.e. after a few nights).
Sleep and the Environment
It is advisable to maintain a higher room temperature for bedrooms, especially for children, because they are more susceptible to the physiological changes than adults. Warm clothes also help maintain the body temperature. Apparels like long-sleeved and heavy sleepwear should be worn to keep the body warm. Researchers have studied the impact of clothing in cold weather, and found that the above-mentioned conditions reduce amongst those who wear clothes that maintain the warmth in the body.
Hence, to conclude, I can say that although cold can have a significant effect on the quality of sleep, one can safeguard themselves and their family by maintaining the warmth of their sleeping and living areas and by dressing up appropriately to keep their body warm at all times of the day.
Ahmed BaHammam, FACP, FCCP
Professor of Medicine
Director, University Sleep Disorders Center
College ofMedicine, King Saud University