Sleep timing may modulate the effect of sleep loss on testosterone

Clin Endocrinol (Oxf). 2012 Nov;77(5):749-54. doi: 10.1111/j.1365-2265.2012.04419.x.


Background: Sleep loss has been shown to reduce secretory activity of the pituitary-gonadal axis in men, but the determinants of this effect are unknown.

Objective: To discriminate the effects of sleep duration and sleep timing on serum concentrations of luteinizing hormone (LH), testosterone (T) and prolactin (PRL).

Methods: Fifteen young, healthy men (27·1 ± 1·3 years; BMI, 22·9 ± 0·3 kg/m(2) ) were examined in a condition of sleep time restriction to 4 h (bedtime, 02:45 -07:00 h) for two consecutive nights and in a control condition of 8 h regular sleep (bedtime, 22:45-07:00 h). After the second night, serum concentrations of LH, T and PRL were monitored over a 15-h period. In addition, these hormones were measured in serum samples obtained in a further experiment in eight healthy men (24·5 ± 1·1 years; BMI, 23·7 ± 0·6 kg/m(2) ) in the morning after one night of total sleep deprivation, of 4·5 h sleep (bedtime, 22:30-03:30 h), and of regular 7 h sleep (bedtime, 22:30-06:00 h).

Results: Serum LH, T and PRL concentrations showed characteristic diurnal variations across the 15-h period without any differences between the 4- and 8-h sleep conditions. However, total sleep deprivation and 4·5 h of sleep restricted to the first night-half markedly decreased morning T and PRL concentrations (both P ≤ 0·05).

Conclusion: Collectively, our data suggest that the effect of sleep restriction on pituitary-gonadal secretory activity may be modulated by sleep timing. While sleep loss in the early part of the night does not affect T and PRL, early awakening and wakefulness during the second part of the night reduces morning circulating T and PRL concentrations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Humans
  • Luteinizing Hormone / blood
  • Male
  • Prolactin / blood
  • Sleep / physiology*
  • Sleep Deprivation / blood*
  • Sleep Initiation and Maintenance Disorders / blood
  • Testosterone / blood*
  • Wakefulness / physiology


  • Testosterone
  • Prolactin
  • Luteinizing Hormone