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.
Kate Smyth is a sports naturopath, nutritionist and female-centric running coach. She is the founder of the Athlete Sanctuary - a holistic healthcare clinic for athletes of all levels and sporting codes.
Kate has a thirst for knowledge, with two bachelor's and a master’s degree under her belt. She has been involved in sports for many decades and competed for Australia in the Commonwealth Games and Olympic Games marathons with a personal best time of 2 hours 28 minutes.
Kate’s path into high‑performance sport didn’t follow the traditional script. A late bloomer and recreational runner, she found her spark during the Sydney 2000 Olympics, watching her idols surge into the stadium. That moment ignited a commitment that would quietly and profoundly reshape the course of her life.
Eight years later, she realised her own Olympic dream, representing Australia in the women’s marathon at the 2008 Beijing Olympic Games.
Her running career spanned the Commonwealth Games, multiple Australian representative teams, and national‑level competition across cross‑country, track, and road racing. With a marathon personal best of 2:28, Kate was one of Australia’s all time fastest female marathoners.
But her journey was far from linear. Significant health challenges forced her to question conventional medicine, sports nutrition and traditional training models. What felt like setbacks at the time became turning points, pushing her to explore deeper, listen more closely to her body, and ultimately develop a more sustainable, female‑centred approach to performance.
These experiences now form the foundation of the work she shares with other women: how to train smarter, nourish deeply, honour physiology, and build resilience from the inside out.
She holds three degrees including a Masters and Bachelor of Health Science (Naturopathy). Kate is an accredited athletics coach with Athletics Australia and a member of NHAA.
Kate’s expertise is widely recognised, leading to regular invitations to speak on podcasts, at seminars, within industry education forums, and across corporate and women’s health initiatives.
