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.