Preserved circadian rhythms reflected by dim light melatonin onset in patients with KLS

To investigate the changes in the phase and amplitude of circadian rhythms in Kleine-Levin Syndrome (KLS) during the remission and relapse phases.

Twenty KLS patients (mean age 19.8 ± 8.7 years) and 46 age-, sex-, and body mass index-matched healthy controls (mean age 19.9 ± 4.5 years) were recruited. Habitual sleep-wake patterns and rest-activity rhythms were recorded using two-week wrist-worn actigraphy. 24-hour serum melatonin profiles were collected to assess circadian markers, including dim light melatonin onset (DLMO), acrophase, amplitude, and midline-estimating statistic of rhythm (MESOR).

Habitual sleep-wake timing did not differ significantly between healthy controls and KLS patients in remission, with no significant differences in sleep onset (23:52 ± 0.9 h vs. 23:16 ± 1.4 h, p = 0.092) or sleep offset (07:52 ± 0.9 h vs. 07:35 ± 1.2 h, p = 0.298). Similarly, rest-activity rhythms were comparable between healthy controls and KLS patients during remission, and major circadian melatonin parameters-including DLMO, acrophase, amplitude, and MESOR-were comparable among the groups during both remission and relapse phases. Specifically, no significant differences were found in DLMO 10 pg timing (21:23 ± 1.2 h vs. 21:59 ± 1.9 h vs. 21:40 ± 2.9 h; p = 0.548) or melatonin amplitude (40.1 ± 19.1 vs. 32.9 ± 26.3 vs. 37.2 ± 24.9 pg/mL; p = 0.590).

The data suggests that endogenous melatonin profiles during both remission and relapse phases appear to be preserved in KLS patients.