A person's sex affects how they sleep, the functioning of their biological clock and, consequently, their metabolism, so it should be taken into account when treating sleep and metabolic disorders. This is stated in an article published in Sleep Medicine Reviews by a team of researchers from the University of Southampton (United Kingdom) and Stanford and Harvard Universities (United States) who have reviewed the existing scientific evidence on sex differences. when it comes to sleep, circadian rhythms and metabolism.
The authors of the article found that sex differences not only correlate with different sleep disorders for men and women, but are also present in biological clocks, which follow different patterns. Some of the studies they have reviewed suggest that women's intrinsic circadian periods are approximately six minutes shorter than men's.
"While this difference may seem small, it is significant; the misalignment between the central biological clock and the sleep/wake cycle is approximately five times greater in women than in men; imagine if someone's clock consistently ticked six minutes longer faster or slower; over the course of days, weeks and months, this difference can cause a noticeable mismatch between the internal clock and external signals, such as light and dark," explained Dr. Renske Lok of the University of Stanford, who led the review.
And he recalled that alterations in circadian rhythms are related to various health problems, including sleep disorders, mood disorders and deterioration in cognitive function.
In their review, the researchers have also detected that men tend to have later chronotypes, that is, they tend to prefer to go to bed and wake up later than women, which can cause a mismatch with respect to social schedules and that their circadian rhythm do not align with social demands such as work.
The article also explains that, in general, women rate their sleep quality worse than men and report more fluctuations often related to changes throughout the menstrual cycle.
On the other hand, women are between 25% and 50% more likely to develop restless legs syndrome and up to four times more likely to develop an eating disorder related to sleep, or more specifically to impulsive eating. overnight.
In the case of men, researchers say, they are three times more likely to be diagnosed with obstructive sleep apnea, a disorder that also appears to have different consequences depending on sex: it is associated with a higher risk of heart failure in women but not in men.
Laboratory sleep studies have also found that women enter REM sleep (characterized by high levels of brain activity and vivid dreams) earlier than men and spend about eight minutes longer than men in non-REM sleep (where brain activity slows down).
The lead author of this review article, Dr Sarah L. Chellappa, from the University of Southampton, commented: "Women are also more likely than men to be diagnosed with insomnia, although the reasons are not entirely clear." , and has emphasized the importance of "recognizing and understanding sex differences in sleep and circadian rhythms to adapt treatment approaches and strategies in these types of disorders and in the mental health conditions that are associated with them, such as anxiety and depressive disorders (which are twice as common in women as in men)."
The researchers also looked at whether the rise in obesity seen in most Western societies could be partially related to people not getting enough sleep. And they observed big differences in how women's and men's brains respond to food images after getting little sleep. Brain networks associated with cognitive (decision-making) and affective (emotional) processes were twice as active in women as in men.
Despite this difference in brain activity (also observed in other studies on the response to sweets), men are more likely than women to overeat in response to lack of sleep.
On the other hand, they also found that, although both men and women are more likely to develop type 2 diabetes if they work night shifts, the risk is higher in men.
Other contrasted evidence collected in the article is that women and men respond differently to treatments for sleep and circadian disorders.
