Until recently, it was widely believed that the main function of sleep was to prevent sleepiness during the day, and the health effects of sleep deprivation were largely unknown.
It is now believed that adults require approximately 8 hours of sleep each night. The negative effects of sleep deprivation are more likely to present in individuals who get significantly more or less than this amount.
It is worth noting that the impact of sleep deprivation reduces as individuals get older, and it is believed that elder individuals require less sleep for healthy function as compared to children or adolescents.
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Weight gain and obesity
Sleep deprivation is linked to weight gain and obesity in both adults and children, with sleep time less than 7 hours per night related to a higher body mass index (BMI).
Some evidence has shown a U-shape curve for sleep duration and obesity, with individuals who have approximately 8 hours of sleep per night with the lowest BMI, whereas both higher and lower sleep times are associated with an increase in weight gain.
Diabetes and impaired glucose tolerance
Loss of sleep has been associated with impaired glucose tolerance and diabetes. These conditions are marked by an abnormally high level of glucose in the blood for an extended period of time following a meal or diagnostic injection of glucose.
One study found that middle-aged adults who self-reported to have 5 hours or less of sleep per night were 2.5 times more likely to suffer from diabetes. Diabetes is also closely linked to obesity, and the increased risk of diabetes may be associated with weight changes observed in sleep deprivation.
Cardiovascular disease
Some epidemiological research has also linked deprivation of sleep to an increased risk of cardiovascular events, such as myocardial infarction and stroke. It is unclear, however, if this is a direct result of reduced sleep quality or as a consequence of increased incidence of obesity and diabetes.
The mechanism that is responsible for increasing the risk of cardiovascular events may involve changes in blood pressure, the sympathetic nervous system, or impaired glucose tolerance.
Sleep Deprivation and its Weird Effects on the Mind and Body
Mood and behavior
Changes in mood and behavior are usually the first signs that become evident in individuals with sleep deprivation, even in the early stages of the condition.
Adults who are affected by chronic sleep deprivation are more likely to report symptoms of depression, anxiety, and mental distress, consume high amounts of alcohol and have a higher risk of suicide. However, it remains unclear if chronic sleep deprivation causes these effects or if changes in mood and behavior are responsible for insomnia and the presentation of sleep deprivation.
Cognition and motor functions
The effects of sleep deprivation on the cognitive performance of individuals are only beginning to be understood with current sleep research.
It is known that lack of sleep is linked to slower reaction times and greater variability in individual performance, which is particularly evident from activities that require a high level of alertness, attention, and vigilance. However, the long-term effect of sleep deprivation on memory and perception is less clear.
Immune system
It is also believed that sleep is needed to strengthen the immune system and the defense of the body against bacterial and viral infection. This link has been suggested from observations of increased sickness in individuals who are sleep deprived, both over short- and long-term periods of time.
References
Further Reading
BMI influences efficacy of nerve-stimulation treatment for sleep apnea, study finds