Sleep propensity free-runs with the temperature, melatonin and cortisol rhythms in a totally blind person

In previous studies, we found that many totally blind people have free- running melatonin rhythms but that free-running melatonin rhythms were not necessarily associated with periodic insomnia and daytime sleepiness. Thus, it was not clear if the circadian sleep propensity rhythm was free-running with the other circadian rhythms. In the present study, we report that the sleep propensity rhythm (as defined by an ultrashort sleep-wake schedule) free-ran with the melatonin, temperature and cortisol rhythms in a 44-year- old totally blind man even though he maintained a conventional sleep schedule and did not complain of clinically significant insomnia or excessive daytime sleepiness.