Experimental sleep curtailment causes wake-dependent increases in 24-h energy expenditure as measured by whole-room indirect calorimetry.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 24088722 · doi:10.3945/ajcn.113.069427
What was done
Ten females aged 22-43 y with a BMI of 23.4-27.5 completed a randomized crossover trial comparing short sleep (4 h/night) and habitual sleep (8 h/night) for 3 d, separated by a 4-wk washout period. Standardized weight-maintenance meals were provided at fixed times (0800, 1200, 1900, snack at 1600). Energy expenditure (EE) and respiratory quotient (RQ) were measured using whole-room indirect calorimetry during the sleep episode on day 2 and continuously over 23 h on day 3.
What was found
Short sleep significantly increased 24-h EE compared with habitual sleep (1914.0 ± 62.4 vs 1822.1 ± 43.8 kcal; P = 0.012), representing an increase of ~92 kcal (~5%). EE during scheduled sleep episodes and across the daytime waking episode (0800-2300) did not differ between conditions. Sleep restriction had no significant effect on RQ.
Why it matters
Prolonged nocturnal wakefulness carries only a modest energetic cost (~92 kcal/d), suggesting that weight gain associated with short sleep is driven by energy intake exceeding this slight increase in expenditure.
Limits
Sample size was very small (10 participants) and included only females within a narrow BMI range. The intervention lasted only 3 days under highly controlled metabolic chamber conditions, leaving longer-term adaptations and free-living dietary compensation unaddressed.
Cited by
- supports In a whole-room indirect calorimeter (metabolic chamber), total 24-hour energy expenditure in women increased by approximately 5% (around 90 calories) during sleep restriction compared to adequate sleep.
- supports During sleep restriction in a metabolic chamber, the metabolic rate of energy expenditure during waking hours is identical to waking energy expenditure after adequate sleep.