Altered sleep-wake patterns in blindness: a combined actigraphy and psychometric study.
Light plays an important role in the synchronization of the internal biological clock and the environmental day/night pattern. Thus, absence of vision is often associated with both increases in reported sleep disturbances and incidence of free-running circadian rhythms. In this study we discuss variability in the sleep-wake pattern between blind and normal-sighted individuals.



Thirty-day actigraphy recordings were collected from 11 blind individuals without residual light perception and 11 age- and sex-matched normal-sighted controls. From these recordings, we extracted parameters of sleep and wake, including episodes of rest, day-time and night-time sleep periods, and the number of awakenings throughout sleep. A measure of sleep efficiency was derived from these measures for each night-time sleep episode. We also examined complementary measures of sleep quality, using the Pittsburgh Sleep Quality Index, and chronotype, using the Morningness-Eveningness Questionnaire.



Although no group differences were found when averaging over the entire recording period, we found a greater variability throughout the 30-days in both sleep efficiency and timing of the night-time sleep episode in blind participants as compared to sighted control participants. We also confirm previous reports of reduced sleep quality in blind individuals. Notably, the variability in sleep efficiency and in the timing of sleep correlated with the severity of sleep disturbances.



The timing and physiology of sleep are strongly dependent on the endogenous circadian phase; therefore, observed findings support the hypothesis of free-running circadian rhythms as a dominant factor for the sleep disturbances experienced in blindness.
Department of Neuroscience, University of Montreal, Montreal, Quebec, Canada; BRAINlab and Neuropsychiatry Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
S
S
Aubin
Grenoble INP - Phelma, Grenoble, France.
C
C
Gacon
Danish Centre for Sleep Medicine, Rigshospitalet-Glostrup; Department of Clinical Neurophysiology, University of Copenhagen, Copenhagen, Denmark.
P
P
Jennum
BRAINlab and Neuropsychiatry Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark; School of Optometry, University of Montreal, Montreal, Quebec, Canada.
M
M
Ptito
BRAINlab and Neuropsychiatry Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark. Electronic address: kupers@sund.ku.dk.
R
R
Kupers
D056044:Actigraphy / Q000379:methods / Q000706:statistics & numerical data*; D000328:Adult; D001766:Blindness; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012893:Sleep Wake Disorders; D011795:Surveys and Questionnaires; D014851:Wakefulness / Q000502:physiology
Actigraphy; Blindness; Circadian rhythms; Light perception; Sleep disturbances; Sleep efficiency