Sleep duration and regularity
hours / night
The cheapest endocrine intervention that actually works.
Partial sleep restriction raises evening cortisol, lowers next-day T in men, and wrecks insulin sensitivity within nights. Unlike most supplements, the direction here is not an artifact of who can afford a Whoop.
Also called sleep restriction, circadian.
Incident edges
Randomized trial · Moderate
Sleep duration and regularity→Testosterone
Cut sleep, cut T. Small trial, right design, right direction.
Randomized trial · High confidence
Sleep duration and regularity→Cortisol
Sleep debt is an HPA intervention. It is also a HOMA-IR intervention.
Randomized trial · High confidence
Sleep duration and regularity→Insulin resistance (HOMA-IR)
You can buy a continuous glucose monitor or you can sleep. One of these has a trial behind it.
Meta-analysis · High confidence
Sleep duration and regularity→Cognitive performance
Cut sleep, cut attention. The meta is large; the leap to 'sleep your way to a title' is not in it.
Review · High confidence
Alcohol intake→Sleep duration and regularity
Alcohol is a sleep toxin with a sedative costume. It sits upstream of the sleep→T and sleep→cortisol arrows.
Cases
Sources
- R. Leproult et al. (2011). Effect of 1 week of sleep restriction on testosterone levels in young healthy men
- K. Spiegel et al. (1999). Impact of sleep debt on metabolic and endocrine function
- J. Lim et al. (2010). A meta-analysis of the impact of short-term sleep deprivation on cognitive variables
- M. A. Emanuele et al. (2001). Alcohol and the male reproductive system