Chronic sleep restriction adversely effects cognitive performance and mood, resulting in accidents and economic loss. We examined the effects of three nights of sleep restriction on cortical oxygenation, cognitive performance and mood. We studied 14 young adults. All subjects spent ≥8 h/night in bed prior to the study day (sufficient sleep), followed by <4 h/night in bed for 3 days (insufficient sleep). Oxyhemoglobin (oxyHb) levels were measured with near-infrared spectroscopy during a word fluency task, and subjects underwent a continuous performance test-identical pairs version (CPT-IP) and filled out the Profile of Mood States (POMS) questionnaire. Peak oxyHb levels after the first and third insufficient sleep nights were significantly lower than that after the sufficient sleep night. Sustained reaction time after the first and third insufficient sleep nights was significantly shorter than that after the sufficient sleep night. Correct response on the CPT-IP after the first and third insufficient sleep nights was significantly less than after the sufficient sleep night. POMS vigor scores after the first and third insufficient sleep nights were both significantly lower than that after the sufficient sleep night. Fatigue and total mood disturbance scores of POMS were significantly higher after the third insufficient sleep night than those after the sufficient sleep night. Three nights of sleep restriction reduced the cortical oxygenation response, and might impair cognitive performance and promote mood disturbance.

Objective To assess the effects of hypnotics on prefrontal cortex activity in healthy subjects using near‐infrared spectroscopy (NIRS) in a double‐blind, placebo‐controlled crossover trial. Methods Eighteen healthy males received acute doses of ramelteon (8 mg), triazolam (0.125 mg), or placebo in a predetermined randomization schedule, with a washout period of more than 1 week. All subjects performed a verbal fluency task during NIRS assessments at baseline and at 1 and 4 hr post‐dose. The number of words correctly generated during the task (behavioral performance) and scores on the Stanford Sleepiness Scale (SSS) were also recorded at each test time. Results Compared with the placebo, triazolam (0.125 mg) significantly decreased oxyhemoglobin (oxy‐Hb) concentration change in NIRS during the posttask period and significantly increased behavioral performance, whereas triazolam (0.125 mg) and ramelteon (8 mg) significantly increased SSS scores. Conclusions The differential effects of two types of hypnotics on oxy‐Hb change measured by NIRS were observed in acute dosing, suggesting that when assessing brain activity of patients with psychiatric disorders, researchers should consider how certain types of hypnotics can influence brain function. This would also provide useful information to clinicians when prescribing hypnotics suitable for their patients' conditions.