Sleep and health are closely linked. The quality and quantity of sleep are important for our bodily functions including reproduction. Poor sleep and sleep deprivation have been known to cause irregular menses and infertility in females.
T, a 29-year-old lady, is the case in point. She had been suffering from insomnia for the past few years. She attributed it to erratic sleeping habits when she was studying in junior college and university. She was rather lax in her time management, always chatting with her friends or rushing to complete her assignments in the wee hours of the night. She would drink cups of coffee to keep herself sober. The insomnia was made worse after she started working as a forex dealer when she had to call people at different time zones.
Her menses started at the age of 12. The cycles were regular at monthly intervals. She began to have longer cycles occurring every 35 to 40 days during those years in the university. The menstruation became erratic after she started working. She could miss her periods for two to three months at times.
She was slightly overweight with a BMI of 26 (normal for Asians is between 18.5 to 23). Clinical and ultrasound examination of her reproductive system were normal. The blood level of oestrogen, the female hormone, was low.
Physiology of sleep
We spend about one third of our life in sleep. It is a physiological process in which our brain is in a relative state of rest and is reactive primarily to internal stimulus. Why we need to have such a long duration of rest is not well understood.
Sleep is organized in a relatively predictable cyclical pattern between 2 major phases: Non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. It is controlled by two systems located within the brain: the homeostatic processes, which are functionally the body’s “need for sleep” center, and the circadian rhythm which is an internal clock for the sleep-wake cycle.
Association between sleep and ovarian function
Studies assessing the impact of sleep quality and/ or sleep duration on ovarian function have revealed an increased risk of menstrual cycle irregularities if the mean sleep duration was less than 5 hours among adolescents and women of reproductive age.
Poor sleep quality was also associated with an increased incidence of menstrual cycle problems such as longer menstrual flow length or premenstrual syndrome. Insomnia was found to have a twofold increased risk in menstrual cycle irregularity in a study of 287 nurses.
Shift work can impact ovarian function negatively. In a study of over 70,000 nurses, it was found that women who had experienced more than 20 months of rotating shift work were more likely to have irregular menses.
T was getting married in about a year’s time. She understood the negative effects of sleep deprivation on her fertility (please refer to the article Fertility and Sleep in this website). She decided to take a year of sabbatical leave from work. With counselling and medications, her sleeplessness gradually improved and her menses were becoming more regular on recent follow-ups.
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