title: Sleep and daytime sleepiness in retinitis pigmentosa patients.
abstract: OBJECTIVE
  We examined sleep, daytime sleepiness and the ability to stay awake during the day in patients affected with retinitis pigmentosa (RP), to further delineate the role of photoreceptors in the circadian cycle.
  
  
  METHODS
  Twelve individuals diagnosed with RP (40 +/- 8 years) And 12 normally sighted healthy individuals (39 +/- 7 years) matched for age, body mass index (BMI) and sex were selected for the study. Participants had their sleep recorded on two consecutive nights and were monitored on the two following days. On the first day, their ability to stay awake and on the second, their sleep propensity were assessed using the Maintenance of Wakefulness Test (MWT) and the Multiple Sleep Latency Test (MSLT), respectively. Self-report measures were obtained using the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and the Toronto Hospital Alertness Test (THAT).
  
  
  RESULTS
  Subjective daytime sleepiness (ESS: 9 +/- 5 vs. 6 +/- 4, P=0.053) and objectively measured sleep propensity (MSLT: 10 +/- 5 vs. 17 +/- 3 min, P < 0.000) were significantly higher in RP patients than controls, whilst their alertness (THAT: 29 +/- 9 vs. 38 +/- 7, P=0.016) and ability to stay awake (MWT: 21 +/- 9 vs. 29 +/- 2 min, P=0.006) were significantly reduced. Retinitis pigmentosa participants had more disturbed nighttime sleep, with significantly more awakenings (arousal index: 14 +/- 8 vs. 8 +/- 6 h, P=0.039), and tended to have less rapid eye movement (REM) sleep (19 +/- 5 vs. 22 +/- 3%, P=0.094).
  
  
  CONCLUSIONS
  Patients with RP have increased daytime sleepiness, reduced alertness and more disturbed nighttime sleep of poorer quality than their normally sighted counterparts, suggesting an influence of photoreceptor degeneration on the circadian cycle.
authors.affiliation: Institute of Medical Science, University Health Network, The Toronto Western Hospital, Toronto, Ontario, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Ionescu
authors.forename: H S
authors.initials: HS
authors.lastname: Driver
authors.forename: E
authors.initials: E
authors.lastname: Heon
authors.forename: J
authors.initials: J
authors.lastname: Flanagan
authors.forename: C M
authors.initials: CM
authors.lastname: Shapiro
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology; D003863:Depression / Q000453:epidemiology / Q000523:psychology; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008875:Middle Aged; D010786:Photoreceptor Cells / Q000502:physiology; D017286:Polysomnography; D012174:Retinitis Pigmentosa / Q000453:epidemiology*; D012895:Sleep, REM / Q000502:physiology*; D014792:Visual Acuity; D014851:Wakefulness