Thyroid function and response to 48-hour sleep deprivation in treatment-resistant depressed patients.

BACKGROUND Clinical depression is associated with abnormalities of the hypothalamic-pituitary-thyroid axis. Changes in thyroid function during sleep deprivation may be related to its antidepressant effects. METHODS Levels of thyroid-stimulating hormone, tri-iodothyronine, tri-iodothyronine uptake, thyroxine, and free thyroxine were measured before, during, and after a 48-hour sleep deprivation in nine treatment-resistant depressed patients. Clinical state was assessed every 4 hours. A retrospective study of 26 similar patients was added for cross-validation. RESULTS Significant increases in thyroid-stimulating hormone and tri-iodothyronine during sleep deprivation were not correlated with clinical improvement. Sleep deprivation responders had lower tri-iodothyronine uptake levels than nonresponders in both the prospective (p <.02) and the retrospective (p <.03) samples. CONCLUSIONS The lower tri-iodothyronine uptake values in responders may identify a subgroup of depressed patients who respond to sleep deprivation by virtue of some abnormality of the hypothalamic-pituitary-thyroid axis that is temporarily corrected by sleep deprivation.