Blog · Diet and body composition

Restricted sleep and hunger hormones: a study of 12 men

Crossover study of 12 healthy young men: after two days of restricted sleep, ghrelin +28%, leptin −18%, hunger +24%. A group finding.

Updated October 20, 2026

A randomised crossover study from the University of Chicago, published in the Annals of Internal Medicine (2004): two days of sleep restriction, compared with two days of sleep extension, were associated with an average 18% reduction in leptin and a 28% increase in ghrelin, with a 24% increase in self-reported hunger. The participants were 12 healthy young men.

The experimental design: controlled conditions

Participants were under controlled conditions of caloric intake and physical activity.

In this design, the hormonal variations depend on sleep restriction, not on changes in diet or exercise. The authors state the limits: the study included only 12 young men and did not measure energy expenditure.

A couple in an elegant hotel bar in the evening: he smiles while she shows him the Digital Twin figure on her phone.

Ai-generated illustration

The biology of sleep-deprivation hunger

Ghrelin is the only known orexigenic hormone. Leptin is the main anorexigenic hormone.

When ghrelin rises 28% and leptin falls 18% simultaneously, the brain receives a double signal: “I am hungry” and “I am not full”. Following a diet under these conditions becomes harder.

Sleep and diet: what the study shows and what it does not

With two days of reduced sleep, hormonal control of appetite changed in healthy young men. The study did not follow participants for months: it does not say what happens to people who sleep little for years, nor that a diet is bound to fail.

The Digital Twin and this research

The Digital Twin lines up the data your devices write to your phone, such as steps, heart rate and sleep, and shows you how they change over time. It does not measure ghrelin or leptin, it does not calculate risk and it does not diagnose: this research describes groups of people, not you. Ghrelin and leptin are measured with a blood test: whether you need one is for your doctor to decide.

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