It is well known that adequate sleep in terms of duration and quality is important for general well-being. It is recommended that adults aged 18-64 years should have 7 to 9 hours of sleep in 24 hours-time period (US National Sleep Foundation). Short sleep duration is defined as sleeping for less than 6 hours in 24 hours time period. It is estimated that 30% of adults do not have adequate sleep at night. Sleep disorders including insomnia are said to be more common in women than men.  
Circadian rhythms, often referred to as “body clock” regulates many physiological processes. Many hormones that regulate reproduction, e.g. luteinizing hormone, Thyroid stimulation hormone, testosterone show circadian rhythms under normal sleep conditions. It stands to reason therefore that prolonged disruption of the circadian rhythm (body clock) can lead to altered hormone patterns and result in reproductive disorders. Such disruption of the circadian rhythm can occur in people with sleep disorders and in shift / night workers.
There is growing evidence that sleep disorders including short sleep duration and poor sleep quality can have adverse effect female fertility. A review of available research papers suggests that disruption of the normal circadian rhythm as occurs in sleep disorders such as insomnia, shift and night workers can affect female reproductive function. The effects include:
  1. Menstrual cycle irregularity, defined as having a cycle of less than 21 days or greater than 35 days at least once over a six-month period
  2. Women with a sleep disorder have a higher risk of subfertility compared to women without
  3. Flight attendants experience constant circadian disruption through jet lag. One research study found that flight attendants have an increased risk of subfertility
  4. There is some evidence that shift work especially at night may be associated with increased risk of spontaneous miscarriage
  5. Short sleep duration may reduce the number of eggs produced in women undergoing IVF cycle
  6. Circadian disruption may impact negatively on embryo quality
Shift work especially at night is an occupational factor that can have adverse effects on fertility. Fertility care providers and women on TTC journey should be aware so they can manage their situation appropriately.

Mr J. Adeghe PhD, FRCOG.