Chronic sleep restriction results from a number of factors; medical condition and social demands, and has adverse effects on daytime function, such as cognitive function and driving performance. We demonstrated that the acute sleep restriction (time in bed < 4 h/night) impaired cortical oxygenation response during word fluency task.

We examined the chronic effect of insufficient sleep on cerebral blood flow and cognitive function.

Ten healthy adults (mean age 19.0 years, mean BMI 22.5 kg/m2) were enrolled in this study. All participants spent > or = 8 h/night in bed prior to study day (sufficient sleep), followed by < 4 h/night in bed for 3 days (insufficient sleep1, 2 and 3). The oxyhemoglobin (oxyHb) level by a word fluency task was measured with a near-infrared spectroscopy recorder on the morning following sufficient and insufficient sleep 1 and 3. Wisconsin card sorting test (WCST), continuous performance test -identical pairs version (CPT-IP) and 2-back test were evaluated on the same day.

The peak oxyHb during the word fluency task was significantly reduced after insufficient sleep 1 and 3 than that after sufficient sleep. The percentage of correct responses on CPT-IP and 2- back test after insufficient sleep 3 were lower than those after sufficient sleep, though there were no significant differences on those. WCST did not significantly differ among insufficient sleep 1 and 3 and sufficient sleep.

The chronic sleep restriction reduced cortical oxygenation response, and might result in cognitive performance impairment.