Changes in Serum TSH and Free T4 during Human Sleep Restriction

STUDY OBJECTIVES: To examine whether recurrent sleep restriction is accompanied by changes in measures of thyroid function. DESIGN: Two-period crossover intervention study. SETTING: University clinical research center and sleep laboratory. PARTICIPANTS: 11 healthy volunteers (5F/6M) with a mean (+/- SD) age of 39 +/- 5 y and BMI 26.5 +/- 1.5 kg/m2. INTERVENTION: Randomized exposure to 14 days of sedentary living with ad libitum food intake and 5.5- vs. 8.5-h overnight sleep opportunity. MEASUREMENTS AND RESULTS: Serum thyroid-stimulating hormone (TSH) and free thyroxine (T4) were measured at the end of each intervention. Partial sleep restriction was accompanied by a modest but statistically significant reduction in TSH and free T4, seen mainly in the female participants of the study. CONCLUSIONS: Compared to the well-known rise in TSH and thyroid hormone concentrations during acute sleep loss, tests obtained after 14 days of partial sleep restriction did not show a similar activation of the human thyroid axis.