Does a change in sleep timing increase testosterone in young adult men?

Abstract

Men are more evening oriented than women. These sex difference might be a result of gonadal hormones, especially of testosterone. Here, we tested for a causal relationship by shifting the sleep timing of young men to one hour later and assessed the influence on saliva testosterone. 50 men participated in our study (31 experimental, 19 control group). Sleep timing was measured with actigraphy. One week served as baseline and afterwards, participants were randomly assigned to either the control or the experimental group. In the experimental group, men were asked to go to bed about one hour later and to sleep one hour longer in the morning. Participants in the control group experienced no significant changes in sleep timing. In the experimental group, participants went to bed later and woke up later; therefore, mid-point of sleep was shifted to a later time and sleep duration decreased, because he men went to bed about one hour later but woke up only about 30 min later. The control group experienced a decline in testosterone, but the experimental group not. Changes in mid-point of sleep between baseline week and experimental week were correlated with the change in testosterone (r = 0.285).

Keywords:

• Chronotype
• mid-point of sleep
• sleep schedule change
• testosterone

Acknowledgments

We are grateful to all men who participated in this study and for their patience in filling the questionnaires and in their kindness applying the actigraphy and donating saliva samples. The study was partly supported by the Gips-Schüle Stiftung.