Changes in Female Astronauts	Changes in Male Astronauts
Alterations in Estrogen hormone secretion	Alterations in Testosterone hormone secretion.
Hormone fluctuations due to altered menstrual cycle, disturbed circadian rhythm and changes in the body composition	Mechanism behind testosterone alteration is unknown, but it causes stress, disrupted sleep pattern, altered physical activity and change in circadian rhythm in the male astronauts.
Altered Estrogen even has an impact on the bone density of female astronauts.	Altered testosterone levels even have an impact on the secretion of the Growth hormone in the male astronauts.
Irregular menstrual cycle is even associated with disruptions in hypothalamic-pituitary-ovarian axis, which in turn elevates stress and alters the energy balance.	Reduced mechanical loading and even altered muscle stimulation can affect the bone density.