Sleep duration and regularity → Cortisol

Mechanism

Spiegel, Leproult, and Van Cauter restricted eleven young men to four hours in bed for six nights, then compared that week with six nights of twelve-hour recovery. Evening cortisol was higher after the short nights. Glucose tolerance also fell in that week; that is a different pair. Voderholzer and colleagues randomized eighty-eight healthy adolescents to four nights at 9, 8, 7, 6, or 5 hours in bed. They sampled saliva cortisol every half hour in the evening and the morning, before and after the last experimental night. Objective sleepiness rose as the nights got shorter. Evening and morning cortisol did not. The authors suggest sleep itself may have compensated. The two trials are not the same exposure. Spiegel used a hard inpatient debt in young men against long recovery. Voderholzer used a graded four-night cut in adolescents and saliva at the edges of the night. Hours in bed can move cortisol. A milder adolescent week did not.

Caveats

Spiegel is eleven men and one inpatient week. The comparison is twelve-hour recovery nights, not habitual sleep. Evening cortisol is the named finding. Voderholzer is larger and still short: four nights, saliva at dusk and dawn, adolescents. Sleepiness rose; cortisol did not. That is a real result in a different population, not a copy of Spiegel. It does not erase the young-men trial. It also does not say that every short week raises cortisol in teenagers. Daytime sleepiness from Voderholzer is not this pair. The stamp is robust causal because Spiegel already ran a restriction trial. A second paper does not make that more certain.

Effect

qualitative. Spiegel 1999 (N=11): 6 nights of 4 h bed raised evening cortisol. Voderholzer 2012 (N=88 adolescents): 4 nights of 5-9 h TIB did not move saliva cortisol.

Nodes

Papers

• Impact of sleep debt on metabolic and endocrine function

  K. Spiegel, R. Leproult, E. Van Cauter · 1999 · The Lancet

• The impact of increasing sleep restriction on cortisol and daytime sleepiness in adolescents.

  U Voderholzer, H Piosczyk, J Holz, B Feige, B Loessl, M Kopasz, D Riemann, C Nissen · 2012 · Neuroscience letters