Sleep is not merely a period of rest, but an active biological process during which metabolism, the immune system, and the secretion of many hormones are regulated. Reproduction is controlled by the circadian rhythm, the body’s internal “clock” that synchronizes the body with the day-night cycle. Hormones involved in reproductive function, such as LH, FSH, estrogens, progesterone, and testosterone, exhibit daily fluctuations, while the hypothalamus—the center that connects the brain to the reproductive endocrine system—is also influenced by light and sleep.

Chronic sleep deprivation, irregular schedules, and working night shifts can disrupt this synchronization. However, this does not mean that a single sleepless night can cause infertility; the scientific debate focuses primarily on chronic sleep and circadian rhythm disorders.

In recent years, evidence regarding the link between sleep and fertility has been growing, though it has not yet been proven that poor sleep alone is a cause of infertility. A 2024 systematic review on female fertility found that poor sleep quality, insomnia, very late bedtimes, and certain disorders, such as obstructive sleep apnea, are associated with poorer reproductive health outcomes, although the results regarding sleep duration are not always consistent.

In men, a meta-analysis showed that sleep disorders are associated with lower total sperm count and concentration, reduced progressive motility, and poorer morphology. Data from assisted reproduction are also of interest: a recent systematic review and meta-analysis of women undergoing IVF/ICSI confirms that sleep disturbance may be a potentially modifiable factor associated with treatment outcomes,

but it emphasizes that we do not yet know whether improving sleep actually leads to more pregnancies or births.

So what can someone trying to conceive do? First and foremost, treat sleep as part of an overall healthy lifestyle and not as yet another source of stress. For most adults, at least seven hours of sleep on a regular basis is recommended, with relatively consistent bedtimes and wake-up times. Reducing bright light and screen use late at night, getting exposure to natural light in the morning, regular physical activity, and limiting caffeine and alcohol close to bedtime can help maintain a stable sleep-wake cycle.

Persistent insomnia, loud snoring, frequent awakenings, or excessive daytime sleepiness warrant medical evaluation, particularly in cases of infertility or polycystic ovary syndrome, where sleep apnea appears to be more common. For now, however, sleep should not be presented as a “fertility treatment”: it is an important and potentially modifiable health factor for which there is growing evidence of an association with reproduction, but not yet sufficient evidence that improving it on its own increases the likelihood of conception.