Regional cerebral metabolic correlates of WASO during NREM sleep in insomnia.
OBJECTIVE
To investigate the non-rapid eye movement (NREM) sleep-related regional cerebral metabolic correlates of wakefulness after sleep onset (WASO) in patients with primary insomnia.


METHODS
Fifteen patients who met DSM-IV criteria for primary insomnia completed 1-week sleep diary (subjective) and polysomnographic (objective) assessments of WASO and regional cerebral glucose metabolic assessments during NREM sleep using [18F] fluoro-2-deoxy-D-glucose positron emission tomography. Whole-brain voxel-by-voxel correlations, as well as region of interest analyses, were performed between subjective and objective WASO and relative regional cerebral metabolism using the statistical software SPM2.


RESULTS
Subjective WASO was significantly greater than objective WASO, but the 2 measures were positively correlated. Objective WASO correlated positively with the percentage of stage 2 sleep and negatively with the percentage of stages 3 and 4 sleep. Both subjective and objective WASO positively correlated with NREM sleep-related cerebral glucose metabolism in the pontine tegmentum and in thalamocortical networks in a frontal, anterior temporal, and anterior cingulate distribution.


CONCLUSIONS
Increased relative metabolism in these brain regions during NREM sleep in patients with insomnia is associated with increased WASO measured either subjectively or objectively. These effects are related to the lighter sleep stages of patients with more WASO and may result from increased activity in arousal systems during sleep and or to activity in higher-order cognitive processes related to goal-directed behavior, conflict monitoring, emotional awareness, anxiety, and fear. Such changes may decrease arousal thresholds and/or increase perceptions of wakefulness in insomnia.
Nofzinger
Eric A
EA
Western Psychiatric Institute and Clinic, Sleep Neuroimaging Research Program, Department of Psychiatry, University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA 15213-2593, USA. nofzingerea@upmc.edu
Nissen
Christoph
C
Germain
Anne
A
Moul
Douglas
D
Hall
Martica
M
Price
Julie C
JC
Miewald
Jean M
JM
Buysse
Daniel J
DJ
D000328:Adult; D001921:Brain / Q000378:metabolism*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D017286:Polysomnography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012720:Severity of Illness Index; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18