TEMPORAL LINK BETWEEN PLASMA THYROTROPIN LEVELS AND ELECTROENCEPHALOGRAPHIC ACTIVITY IN MAN

Plasma thyrotropin (TSH) levels have been previously shown to be assoc iated with the internal sleep structure determined by conventional sco ring of sleep stages. This temporal relationship was re-evaluated usin g spectral analysis of the sleep electroencephalogram (EEG). Eight hea lthy male subjects underwent two randomized night studies after having received either placebo or 5 mg ritanserin, a selective 5-HT2 recepto r antagonist known to increase slow-wave sleep. Delta relative power a nd TSH levels, determined at 10 min intervals, were found to be invers ely related with an average cross-correlation coefficient highly signi ficant (P < 0.0001) in both experimental conditions. Alpha slow-wave i ndex, an estimator of awakenings, and TSH pulses exhibited a significa nt temporal association in both conditions. These results demonstrate that TSH fluctuations are linked to the sleep EEG activity in man.