Translation guide
A very brief, involuntary episode of sleep or loss of attention, often lasting a few seconds, typically caused by fatigue or sleep deprivation.
Describing a momentary, unintended lapse into sleep, often while trying to stay awake.
Describing a momentary lapse in concentration, not necessarily involving actual sleep, but a blanking out.
Microsleep is involuntary and often dangerous. Do not use words like 昼寝 (ひるね, nap) or 仮眠 (かみん, catnap) which imply intentional rest.
Microsleep is completely different from a nap.
The direct loanword from English, widely understood in medical and technical contexts. It refers specifically to the phenomenon of brief, involuntary sleep episodes.
It is extremely dangerous if a microsleep occurs while driving.
Literally 'a momentary doze.' A more colloquial way to describe a microsleep episode, emphasizing the briefness and involuntary nature.
I had a momentary microsleep during the meeting.
A more literal translation, 'momentary sleep.' Used in formal or medical explanations but less common in everyday speech.
Momentary sleep can occur due to lack of sleep.
When you're tired, momentary lapses of consciousness become more likely.
A common verb meaning 'to zone out' or 'to be spaced out.' It captures the loss of focus aspect, though it may not imply actual sleep.
I zoned out while driving and almost had an accident.
A noun meaning 'distraction' or 'inattention.' It describes a state of reduced focus, which can be a result of microsleeps, but is a broader term.
Working in a state of inattention leads to mistakes.
The loanword マイクロスリープ is the most precise term and is understood by many Japanese speakers, especially in contexts like driving safety or sleep science. In casual talk, you can describe the experience with phrases like 一瞬寝てしまった (I fell asleep for a moment).