Nocturnal Dynamics of Sleep-Wake Transitions in Patients With Narcolepsy

Sleep. 2017 Feb 1;40(2). doi: 10.1093/sleep/zsw050.


Introduction: We investigate how characteristics of sleep-wake dynamics in humans are modified by narcolepsy, a clinical condition that is supposed to destabilize sleep-wake regulation. Subjects with and without cataplexy are considered separately. Differences in sleep scoring habits as a possible confounder have been examined.

Aims and methods: Four groups of subjects are considered: narcolepsy patients from China with (n = 88) and without (n = 15) cataplexy, healthy controls from China (n = 110) and from Europe (n = 187, 2 nights each). After sleep-stage scoring and calculation of sleep characteristic parameters, the distributions of wake-episode durations and sleep-episode durations are determined for each group and fitted by power laws (exponent α) and by exponentials (decay time τ).

Results: We find that wake duration distributions are consistent with power laws for healthy subjects (China: α = 0.88, Europe: α = 1.02). Wake durations in all groups of narcolepsy patients, however, follow the exponential law (τ = 6.2-8.1 min). All sleep duration distributions are best fitted by exponentials on long time scales (τ = 34-82 min).

Conclusions: We conclude that narcolepsy mainly alters the control of wake-episode durations but not sleep-episode durations, irrespective of cataplexy. Observed distributions of shortest wake and sleep durations suggest that differences in scoring habits regarding the scoring of short-term sleep stages may notably influence the fitting parameters but do not affect the main conclusion.

Keywords: cataplexy; exponential distribution; narcolepsy; power-law distribution; sleep scoring; sleep–wake dynamics; wake-episode durations.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cataplexy / diagnosis
  • Cataplexy / epidemiology
  • Cataplexy / physiopathology
  • Child
  • Child, Preschool
  • China / epidemiology
  • Europe / epidemiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Narcolepsy / diagnosis*
  • Narcolepsy / epidemiology
  • Narcolepsy / physiopathology*
  • Sleep / physiology
  • Sleep Stages / physiology*
  • Young Adult