Age and time-of-day differences in the hypothalamo-pituitary-testicular, and adrenal, response to total overnight sleep deprivation.

Plain-language summary

This study set out to compare how young and older men's hormone levels respond to a night without sleep. It measured testosterone, luteinizing hormone (LH, a pituitary hormone that signals the testicles to make testosterone, so a fall in it means less signal to produce any) and cortisol in 35 healthy men, 17 aged 18 to 30 and 18 aged 60 to 80, across a night of total sleep deprivation and a normal night. Missing a night's sleep lowered testosterone across the day, cut LH in the morning in both age groups, and raised cortisol in the afternoon in the older men. The authors describe this as the timing of the control system coming uncoupled rather than as a change in the overall amount. Two other studies in this library, on catch-up sleep and on five nights of restricted sleep, share an author with this one, so the three are not independent of each other.

Key findings

• Sleep deprivation reduced testosterone levels, particularly in older men.
• Testosterone secretion, pulse frequency, and basal levels all dropped after a night without sleep.
• Older men showed more significant changes in pulsatile testosterone secretion and pulse frequency compared to younger men.
• Cortisol levels rose in the afternoon in older men after sleep deprivation.
• Luteinizing hormone (LH) dropped in the morning in both age groups, but overall LH changes were not significant.