Why Poor Sleep Can Lead to Lighter or Delayed Periods

The menstrual cycle acts as a monthly report card on how well the body is balancing energy, demands, and recovery.  Alarmingly, 37% of female athletes have menstrual irregularities, with many unaware of the long-term health implications.

Sleep plays an important role not only in recovery, but also in regulating the menstrual cycle. If we rule out pregnancy, active females, can have many factors collectively contributing to lighter or irregular menstraul cycles, all of which are important to understand but also address. Let's recap some of the most common issues that contribute to lighter or delayed periods.

Why Periods May Stop or Become Irregular

High exercise volume or intensity. When training volume or intensity increases, the body may shift priorities and redirect energy away from reproduction and toward survival and performance. In simple terms, the brain tells the ovaries to take a break and periods can become irregular, delayed, or stop altogether. A recent systematic review found that approximately 32.3% of female athletes are impacted in this way.

Nutritional factors. Low energy availability (not eating enough to match output) and restrictive eating are the most common nutritional issues which impact the cycle.  When calorie intake does not match the high energy expenditure of training, the body conserves fuel by slowing reproductive function, and hormones such as oestrogen and progesterone start to decline. While many women boast a quality nutritional profile on the surface, the calorie intake or density can still be insufficient to match the demands of the individual.

Skipping snacks or having lighter meals can easily tip athletes into the red. Prolonged energy depletion can lead to issues such as Relative Energy Deficiency in Sport. Athletes with or without an eating disorder may choose to restrict food intake during a determined window to make weight or enhance performance for a key event. This can impact body fat, hormone signalling and extend the cycle, lighten cycles or stop them altogether.

Emotional stress and anxiety

Emotional stress, travel, competition anxiety, or personal challenges can elevate cortisol and disrupt the hypothalamic-pituitary-ovarian (HPO) axis. The pressure to perform, coupled with life stressors, can compound physical strain, further suppressing hormones that regulate menstruation. Stress of any kind raises cortisol, directly suppresses the HPO axis, and reduces hormones such as progesterone, leading to missed cycles and functional hypothalamic amenorrhea. A condition where the brain suppresses reproductive function due to perceived stress or energy deficiency.

Low Iron

Iron deficiency can indirectly contribute to lighter cycles. Iron deficiency elevates cortisol and inflammatory markers and has effects on the HPO axis as explained above. Estrogen levels may then drop, especially if iron deficiency is paired with low energy availability. The cycle can then start to pitter out. Energy production can also be impacted despite meeting calorie needs.

Poor sleep and recovery habits

Sleep is when the body recalibrates its hormonal systems. During deep sleep, the HPO axis relies on stable circadian rhythms to regulate the release of gonadotropin-releasing hormone (GnRH). This hormone triggers the production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are essential for ovulation and menstrual regularity.

When sleep is fragmented or insufficient, cortisol levels rise, melatonin drops, and GnRH pulsatility becomes irregular, disrupting circadian rhythm and impairing ovulation. This vicious cycle contributes to irregular cycles. Poor recovery from poor sleep also dysrupts the HPO axis and cases light or missed periods.

This feedback loop can persist unless addressed through improved sleep hygiene, balanced nutrition, and structured recovery strategies.

Why It Matters

Menstrual irregularities are not just about missed periods. They can affect bone density, cardiovascular health, mood, and fertility. For sportswomen, understanding this connection is empowering. It allows for proactive choices such as adjusting training, improving nutrition, and seeking guidance when needed.

A delayed period is useful feedback. It is the body’s way of saying, “I need more care.” By listening, adjusting, and supporting our hormones, we create space for both strength and sustainability.

At Athlete Sanctuary, we believe that performance and health are not opposing forces. They are partners. If you would like to improve your report card, we are here to help.