Research

Hormonal

Sleep restriction (4 hours/night) increases evening cortisol levels and delays the nocturnal nadir, while simultaneously decreasing TSH levels and amplitude, indicating a disruption of the hypothalamo-pituitary-adrenal and thyroid axes.

Short sleep doesn't just make you tired; it shifts your stress hormones (cortisol) to be higher in the evening and lowers thyroid-stimulating hormone (TSH). This hormonal imbalance contributes to metabolic stress. Prioritizing 8 hours of sleep helps normalize these rhythms.

GoodSupportsHIGH confidence
Cortisol levels in the late afternoon and evening (1600-2100 h) were higher after sleep restriction... and the nadir occurred approximately 1.5 h later... After sleep restriction, mean 24-h TSH levels were 26% lower... and the amplitude of the diurnal variation was reduced by 27%.
Karine Spiegel et al. · The Journal of Clinical Endocrinology & Metabolism · 2004

Why this rating

Controlled crossover design with frequent sampling allows for precise chronobiological analysis.

Source

Leptin Levels Are Dependent on Sleep Duration: Relationships with Sympathovagal Balance, Carbohydrate Regulation, Cortisol, and Thyrotropin

Karine Spiegel et al. · The Journal of Clinical Endocrinology & Metabolism · 2004

DOI 10.1210/jc.2004-1003

crossover · n=11Cited 998×
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DOI resolved against Crossref · corpus check 2026-06-10

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