What does too little sleep do to your testosterone levels?

Complete sleep deprivation of at least 24 hours measurably lowers testosterone in healthy men. Many studies combined show a meaningful drop. That is the clearest link the research has found so far.

Short-term partial sleep loss, the kind most people are familiar with, shows no statistically measurable effect on testosterone in those same studies. The drop that was measured was small and could have been down to chance. So one bad night's sleep is not an immediate reason to worry about a hormone crash.

What does seem biologically plausible: prolonged sleep loss may, through higher cortisol levels and other stress-related processes, affect the cells that produce testosterone. Combinations with large amounts of ultra-processed food are also described as potentially harmful. But these are still hypotheses, not firm findings from studies in people.

One striking finding turns the expected sequence on its head. A large genetic study found that higher testosterone levels in men actually lead to shorter sleep, not the other way around. That study found no evidence that sleep loss lowers testosterone in the general population. This means the link between poor sleep and lower testosterone may also run in the opposite direction, or that both are driven by a third factor.

Extreme circumstances, such as military field training where sleep deprivation goes hand in hand with intense physical effort and limited food intake, do show strong drops in testosterone. But in those situations it is impossible to determine what sleep deprivation alone is responsible for.