Ritanserin, a serotonin-2 receptor antagonist, improves ultradian sleep rhythmicity in young poor sleepers

Objectives: To determine the effect on sleep electroencephalographic (EEG) activity of ritanserin, a serotonin-2 (5-HT2) receptor antagonist in young poor sleepers. Methods: Eight male subjects underwent two randomized night studies after receiving either a placebo or 5 mg ritanserin administered in the morning. The overnight variations in the delta (0.5–4.0 Hz) and sigma (12.25–15.0 Hz) frequency bands were characterized using a peak analysis which provided a quantitative evaluation of the time-courses in EEG activity. Results: In subjects under ritanserin, slow wave sleep duration and the number of non-rapid eye movement (NREM)–REM sleep cycles were significantly enhanced (P<0.01). The number of peaks in delta activity occurring in the normal 80–120 min range was significantly (P<0.05) increased. Using a delta peak analysis, 4 periods containing or not a significant peak were identified in each subject. A significant increase in delta activity was observed in the areas under the averaged curves during the second and the third periods (P<0.05), while sigma activity decreased under ritanserin during the first, second and third periods (P<0.05). Conclusions: These results demonstrate that ritanserin increases delta activity, possibly by opposing the inhibitory control of 5-HT2 receptor family. It restores sleep ultradian rhythmicity and improves sleep quality in young poor sleepers.