Fetching details from the dictionary...
lack of sleep; sleep deprivation
最近は睡眠不足で頭がぼんやりする。
I've been sleep-deprived lately and my head feels foggy.
睡眠不足は健康に悪い。
Sleep deprivation is bad for your health.
睡眠不足が続くと集中力が著しく低下する。
Prolonged sleep deprivation significantly reduces concentration.