When young men slept only 3.5 hours a night for three nights, their bodies produced less of the hormones that tell them they’re full, making them feel hungrier.
Scientific Claim
Three nights of shortened sleep (3.5 hours per night) in healthy young men caused a significant decrease in fasting peptide YY (PYY) levels by 12.5% (from 186.2 to 163.0 ng/mL, p=0.011) and a trend toward reduced glucagon-like peptide-1 (GLP-1) levels (from 2.1 to 1.4 pmol/L, p=0.055), which are associated with increased hunger and reduced fullness.
Original Statement
“Plasma peptide YY (PYY) concentrations were significantly lower after the 3-night sleep restriction in the 3.5-h sleep condition than in the 7-h sleep condition (p = 0.011). Plasma glucagon-like peptide-1 (GLP-1) levels after the 3-night sleep restriction tended to be lower in the 3.5-h sleep condition than in the 7-h sleep condition (p = 0.055).”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
definitive
Can make definitive causal claims
Assessment Explanation
The RCT design with direct hormone measurements under controlled conditions supports causal language. The p-values and effect sizes are clearly reported, justifying definitive verbs.
Evidence from Studies
Supporting (1)
Effect of shortened sleep on energy expenditure, core body temperature, and appetite: a human randomised crossover trial
When these men slept only 3.5 hours a night for three nights, their bodies made less of the hormones that tell them they’re full, so they felt hungrier—even though they didn’t burn more calories.