Hypernychthemeral sleep-wake cycle: some hidden regularities.


A patient with a sleep-wake cycle greater than 24 h recorded his sleep-onset and wake times for 4 years. During this time the patient found himself unable to maintain a 24-h sleep-wake schedule. The lengths of his sleep-wake periods (subjective days) and his sleep periods were highly variable. Nonetheless, there were certain unexpected regularities in his… (More)