**11. Correlation between biology of male reproduction and sleep**

The whole process of spermatogenesis is controlled by hypothalamic pituitary gonadal axis. Hypothalamus secretes GnRH that stimulates the anterior pituitary to secrete LH and FSH. FSH act on the testicular tissue and LH triggers the secretion of testosterone in the testis by Leydig cells. Maximum level of testosterone secretion occurs during sleep. This nocturnal rise in testosterone secretion appears at the same time with the beginning of resting eye movement sleep and it is not concerned with the change in the level of melatonin [68]. In male reproductive system, prolactin hormone secreted by anterior pituitary o has also a key role. Prolactin increases in Leydig cells the utterance of LH receptors at physiological level. The latest leads to increased secretion of testosterone promoting spermatogenesis. The increasing pervasiveness of 24/7 constant distribution of entertainment, disrupts the circadian rhythm and impair the duration and quality of sleep on population level. The schedule of sleep and wake is delayed by the use of electronic devices at night time. More over blue light emitted by LED reduces the secretion of melatonin and thus decreases the prolonged, objective and subjective sleepiness. Sleep restriction disrupts the level of gonadal hormone. The level of testosterone is reduced in 10 volunteer's healthy males in 1 week of restricted sleep. While in another examination of sleep restriction of 4–5 hours in 15 men is also associated with reduction in the level of testosterone. Effect of sleep restriction and resting eye movement deprivation was analyzed by Alvarenga et al. on parameter of sperm and expression of testis specific genes in male rat. Both sleep restriction (SR) and rapid eye movement sleep deprivation (RSD) group has decreased viability of sperm [69].
