Research

Hormonal

Slow-wave sleep (SWS) episodes are temporally associated with a significant decrease in plasma cortisol levels, suggesting an inhibitory relationship or synchronized regulation between deep sleep and adrenocortical quiescence.

Prioritize slow-wave sleep (deep sleep) to help regulate cortisol levels. This study shows that deep sleep phases are strongly linked to drops in cortisol. If you are struggling with high stress or cortisol-related issues, focusing on sleep hygiene to maximize deep sleep duration may be as effective as other stress-management techniques.

GoodSupportsHIGH confidence
SWS episodes were significantly associated with declining plasma cortisol levels (p < 0.01)... The results clearly indicated that SWS phases are associated with diminished adreno-cortical activity.
M. Follénius et al. · SLEEP · 1992

Why this rating

Controlled experimental design with 12 subjects, continuous blood sampling, and rigorous pulse analysis, though limited by small sample size.

Source

Nocturnal Cortisol Release in Relation to Sleep Structure

M. Follénius et al. · SLEEP · 1992

DOI 10.1093/sleep/15.1.21

crossover · n=12Cited 187×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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