Sleep-related problems are increasingly discussed: modern people do not get enough sleep and, fully aware of the importance of night rest, are looking for new technological ways to improve its quality - from "smart" beds with sleep trackers to special sprays for bed linen. But there are problems that are difficult to solve with earplugs or a mobile app. According to the US National Sleep Organization (yes, there is one - The National Sleep Foundation), women are much more likely than men to experience insomnia and other sleep disorders. Scientists have discovered and are actively investigating new factors that may be behind these disappointing statistics.
There is reason to believe that the whole point is in the difference in circadian rhythms, and they, in turn, depend on the level of various hormones, including sex hormones. To understand what this is about, you need to consider that the circadian rhythm is not just an "internal clock" that determines the time of sleep and wake-up. Many other physiological processes, such as the regulation of body temperature, occur within this cycle, equal to about twenty-four hours, also known as the biological day. Changes in sleep and wakefulness, fluctuations in body temperature and other vital functions are triggered by signals from the environment - from sunlight to atmospheric pressure - and a number of chemical elements in the body.
To find out how different people respond to these signals during the day, last year, American scientists decided to study the mechanisms of sleep of fifteen men and eleven women (eight of them participated in the experiment during two different phases of the menstrual cycle). The subjects were asked to fall asleep under carefully controlled conditions for three days. In addition, during the study, group members were shown daytime sleep. Scientists regularly measured the subjects' body temperature, the quality of their sleep, the level of melatonin, a hormone responsible for circadian rhythms, as well as how quickly the group members fell asleep and how alert they were after waking up. The results of the study were unexpected: although male and female organisms underwent the same physiological processes due to circadian rhythms during the day, in women these cycles proceeded faster. Women went to sleep and woke up earlier. “During the day, women went to bed an average of two hours earlier than men,” explains Dr. Diana Boyvin, who conducted the study. “It’s like the system of daily rhythms in women is one time zone to the east than in men.”
Of course, a much wider sample will be required to confirm the results. However, the findings of this study are in good agreement with an earlier one, which showed that a biological day shorter than twenty-four hours is more common among women. In addition, they reported more cases of physical exhaustion after being forced to stay awake at night. The fact that women often wake up earlier than men, scientists explain by changes in hormone levels and body temperature within the daily rhythm. The difference in their duration, as well as physiological fluctuations within the cycle, are considered quite normal and do not cause any complications for most of us. At the same time, such scientific observations bring us closer to understanding why disruptions in the "biological clock" and sleep disorders are more typical for women.
Circadian rhythms affect not only sleep, but also processes such as, for example, the body's response to different types of medications
Although these trials did not find a direct link between the participants' menstrual cycles and the quality of their sleep, another small study from the same laboratory showed that during the luteal phase of the cycle, that is, between ovulation and menstruation, the total amount of sleep in the rapid phase may decrease. Scientists now believe the phenomenon may be related to the work of the suprachiasmatic nucleus, a small collection of neurons in the brain that controls circadian rhythms. This zone regulates the level of production of hormones that determine the mechanisms of sleep and awakening, in particular melatonin. It turned out that estrogen receptors are also located in this nucleus, and it, as you know, regulates the course of the menstrual cycle and all accompanying changes in the body, including body temperature - an important factor in the sleep-awakening system.
Based on these observations, the researchers conclude about another type of connection between the level of hormones and our "internal clock". Dr. Boyvin is quite bold in stating: "Basically, the area of the brain responsible for circadian rhythm and sleep mechanisms has a gender." Another sleep doctor Dianne Augelli, in an interview with New York Magazine, is more careful in expressions, but also confirms the role of sex hormones in the formation of circadian rhythms: “Estrogen works as a neurotransmitter in different ways, some of which affect the quality of sleep, and progesterone can be sleepy properties ". This factor, according to doctors, is of fundamental importance, because circadian rhythms affect not only sleep, but also such processes as, for example, the body's response to different types of medications.
There are also more obvious and well-studied factors that shape the statistics of sleep disorders. In women, this is, for example, pregnancy and menopause. In addition to changes in estrogen and progesterone levels, general physical discomfort can occur during pregnancy, as well as symptoms ranging from burning in the chest to restless legs syndrome, which affects sleep quality. Insomnia and sleep apnea (temporary stopping or weakening of breathing) are frequent companions of pregnancy and menopause. During the latter, it is also known that hot flashes and excessive sweating occur regularly, including at night. In addition, a number of studies prove that women suffer from anxiety more acutely than men and perceive stress more heavily in their professional and personal life - a lot of studies indicate the effect of the "stress hormone" cortisol on sleep disorders.
In any case, scientists have only recently come close to understanding how complex sleep mechanisms actually work and in which cases gender differences do matter. In the existing studies proving the relationship between the level of sex hormones and the duration of circadian rhythms, an insufficient number of subjects are involved. In addition, the participants in such experiments, as a rule, are either completely healthy, or one and all suffer from sleep disorders, so it is difficult to achieve proper data distribution. Nevertheless, researchers already confidently associate the difference in circadian rhythms and levels of sex hormones with the fact that women have more sleep disorders - in particular, they sleep worse closer to morning. How exactly this pattern arises remains to be seen.
Photos: Africa Studio - stock.adobe.com, elizabeth W