Association between delayed sleep phase and hypernyctohemeral syndromes: a case study
Related Experiment Video
Updated: Aug 24, 2026

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Diane B Boivin1, Okan Caliyurt, Francine O James
1Center for Study and Treatment of Circadian Rhythms, Douglas Hospital Research Center, Montreal, Qc, Canada. boidia@douglas.mcgill.ca
Study Objective:
We investigated whether the hypernyctohemeral syndrome (non-24-hour sleep-wake syndrome) may show a clinical association with the delayed sleep phase syndrome (DSPS) in a 39-year-old woman who developed sleep disturbances following a traumatic brain injury.
Measurements And Results:
Sleep-wake log documentation and wrist-activity recordings for more than 6 consecutive months confirmed the patient's tendency to live on longer-than-24-hour "days." Episodes of relative coordination to the 24-hour day were also noted, suggesting that the patient was transiently in and out of phase with environmental synchronizers too weak to fully entrain her to the geophysical environment. Interestingly, we noted a tendency to initiate sleep between 3:00 am and 5:00 am and wake up from sleep between noon and 1:00 pm.
Conclusions:
These results support an association between the hypernyctohemeral syndrome and the DSPS. This association may carry implications for the treatment of circadian rhythms disorders.
Related Concept Videos
Sleep-Wake Cycles
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:
Management of Insomnia
Narcolepsy
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Stages of Sleep
Before sleep begins, in wakefulness, the brain exhibits primarily beta waves, which are high in frequency and low in amplitude, indicating alertness...
Insufficient Sleep and Sleep Deprivation
Sleep deprivation is a more severe form of sleep loss...

