Sleep microstructure around sleep onset differentiates major depressive insomnia from primary insomnia.
In the present study we investigate whether alterations of sleep propensity or of wake propensity are implicated in sleep initiation disturbances encountered in major depressive insomnia and in primary insomnia. For this purpose, the time course of electroencephalogram (EEG) power density during the period preceding sleep onset and during the first non-rapid eye movement (REM) period was examined in three age and gender matched groups of 10 women and 11 men (healthy controls, primary insomniacs and depressive insomniacs). In contrast to healthy controls and depressive insomniacs, patients with primary insomnia did not experience a gradual decrease of their alpha and beta1 power during the sleep onset period and had a lower delta activity in the 5 min preceding sleep onset. Compared with the two other groups, depressive patients exhibit less dynamic changes in slow wave activity during the first non-REM period. The present results suggest that hyperarousal (high 'Process W') may mainly be implicated in the sleep initiation difficulties of primary insomniacs whereas the homeostatic sleep regulation process seems to be partially maintained. In our major depressed patients, the sleep initiation disturbances appeared to relate to a lower sleep pressure (low 'Process S') rather than to hyperarousal. This study supports the idea that different mechanisms are implicated in sleep disturbances experienced by primary insomniacs and major depressive insomniacs.
Staner
Luc
L
FORENAP-Institute for Research in Neurosciences, Neuropharmacology and Psychiatry, Centre Hospitalier, Rouffach, France. luc.staner@forenap.asso.fr
Cornette
Françoise
F
Maurice
Damien
D
Viardot
Geoffrey
G
Le Bon
Olivier
O
Haba
José
J
Staner
Corinne
C
Luthringer
Rémy
R
Muzet
Alain
A
Macher
Jean-Paul
JP
D000328:Adult; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D004585:Electrooculography; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000453:epidemiology; D012895:Sleep, REM / Q000502:physiology; D011795:Surveys and Questionnaires; D013997:Time Factors; D014851:Wakefulness