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/m(2). 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 (14) were measured at the end of each intervention. Partial sleep restriction was accompanied by a modest but statistically significant reduction in TSH and free 14, 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.