Cerebral perfusion differences between drowsy and nondrowsy individuals after acute sleep restriction

Objectives:
To investigate changes in resting cerebral blood flow (CBF) after acute sleep restriction. To investigate the extent to which changes in CBF after sleep restriction are related to drowsiness as manifested in eye-video.

Design:
Participants were scanned for 5 min using arterial spin labeling (ASL) perfusion imaging after both sleep-restricted and rested nights. Participants were rated for visual signs of drowsiness in the eye-video recorded during the scan.

Setting:
Lying supine in a 3-Tesla magnetic resonance imaging scanner.

Participants:
Twenty healthy adults (age 20–37 yr) with no history of neurologic, psychiatric, or sleep disorder, and with usual time in bed of 7.0–8.5 h.

Interventions:
In the night before the sleep-restricted session, participants were restricted to 4 h time in bed.

Results:
There was an overall reduction in CBF in the right-lateralized fronto-parietal attentional network after acute sleep restriction, although this was largely driven by participants who showed strong signs of drowsiness in the eye-video after sleep restriction. Change in CBF correlated with change in drowsiness in the basal forebrain-cingulate regions. In particular, there was a pronounced increase in CBF in the basal forebrain and anterior and posterior cingulate cortex of participants who remained alert after sleep restriction.

Conclusions:
The pattern of cerebral activity after acute sleep restriction is highly dependent on level of drowsiness. Nondrowsy individuals are able to increase activity in the arousal-promoting brain regions and maintain activity in attentional regions. In contrast, drowsy individuals are unable to maintain arousal and show decreased activity in both arousal-promoting and attentional regions.