Impact of five nights of sleep restriction on glucose metabolism, leptin and testosterone in young adult men.
Level 3 - non-randomized controlled study
Non-randomized, single-arm pre-post experimental laboratory trial without a control group.
PubMed 22844441 · doi:10.1371/journal.pone.0041218
What was done
Fourteen healthy young men (mean age 27.4 ± 3.8 years, BMI 23.5 ± 2.9 kg/m²) completed a laboratory-based sleep restriction protocol with controlled caloric intake (~2,000 kcal/day) and restricted strenuous activity. The protocol consisted of 2 baseline nights of 10 h time in bed (22:00–08:00), followed by 5 nights of 4 h time in bed (04:00–08:00), and 1 recovery night of 10 h time in bed. Blood was sampled through an indwelling catheter on baseline day 1 (B1) and sleep restriction day 5 (SR5) at 09:00 (fasting) and every 2 hours from 10:00 to 20:00 to measure glucose, insulin, triglycerides, leptin, cortisol, ACTH, testosterone, and sex hormone binding globulin (SHBG).
What was found
On SR5 compared to B1, glucose (F(1,168) = 25.3, p < 0.001), insulin (F(1,168) = 12.2, p < 0.001), cortisol (F(1,168) = 10.2, p = 0.002), and leptin (F(1,168) = 10.7, p = 0.001) were significantly increased. Triglycerides (F(1,168) = 7.5, p = 0.007) and SHBG (F(1,167) = 12.1, p < 0.001) significantly decreased. No significant changes were found for fasting HOMA-calculated insulin resistance (F(1,168) = 1.3, p = 0.18), ACTH (F(1,168) = 0.3, p = 0.59), or total testosterone (F(1,168) = 2.8, p = 0.089).
Why it matters
This study demonstrates that five consecutive nights of short sleep curtailment rapidly impair glucose regulation and increase daytime cortisol and leptin in healthy young adults under fixed caloric intake.
Limits
The study had a very small sample size (n = 14) and included only healthy young males, limiting generalizability to females, older individuals, or those with baseline metabolic dysfunction. It used a single-arm pre-post experimental design without a parallel non-sleep-restricted control group or randomized crossover design, meaning time in laboratory confinement could be a confounder.
Cited by
- contradicts Sleeping 5 hours a night drops testosterone levels in men by 15% compared to sleeping 8 hours.