睡眠負債

• Reading: すいみんふさい
• Romaji: suimin fusai
• Kanji breakdown: 睡眠 (sleep; 睡 = drowsy + 眠 = sleep) + 負債 (debt; 負 = bear/owe + 債 = debt) → sleep debt, accumulated deficit from insufficient sleep
• Pronunciation: /su.i.miɴ.ɸu.sa.i/

Meaning

Sleep debt — the accumulated deficit from chronically not getting enough sleep, which cannot be repaid by weekend sleeping in.

睡眠負債 became a buzzword in Japan after NHK and other media ran features on the concept, shocking viewers with the revelation that sleep lost during the week cannot simply be 'repaid' by sleeping in on weekends. The term hit a nerve in Japan, where working long hours and sleeping little has long been normalized or even glorified. Research showed that Japanese people average some of the least sleep in the world, and 睡眠負債 gave a concrete, financial-sounding name to the consequences. The 'debt' metaphor resonated with the idea that sleep loss accumulates with interest.

Examples

1. 平日の睡眠負債を週末の寝だめで返すのは無理らしいよ。 Apparently you can't pay off your weekday sleep debt by sleeping in on weekends.
2. 日本人は睡眠負債が世界的に見ても深刻なんだって。 Japanese people's sleep debt is said to be among the worst in the world.
3. 睡眠負債がたまると集中力も免疫力も落ちるから怖い。 When sleep debt piles up, both your focus and your immune system take a hit — it's scary.

Usage Guide

Context: health, media, social media, daily conversation

Tone: cautionary, educational

Do Say

• 睡眠負債やばいから、今日は早く寝る。 (My sleep debt is terrible, so I'm going to bed early tonight.)
• 睡眠負債は週末の寝だめじゃ解消できないんだよ。 (You can't clear sleep debt just by sleeping in on weekends.)

Don't Say

• 「寝てないアピール」は睡眠負債を増やすだけ — 短時間睡眠を自慢しない ('Look how little I slept' bragging just increases sleep debt — don't glorify being sleep-deprived)

Common Mistakes

• Believing 寝だめ (binge sleeping on weekends) can repay 睡眠負債 — research shows irregular sleep patterns actually worsen the problem

Origin & History

Translation of English 'sleep debt' (originally coined by sleep researcher William Dement). Became a major buzzword in Japan around 2017 when NHK featured the concept, raising alarm about Japan's chronic sleep deprivation.

Cultural Context

Era: 2017 NHK feature, buzzword from late 2010s

Generation: All ages, awareness-raising concept

Social background: Universal

Regional notes: Used across all of Japan. Particularly impactful in a culture where sleeping little was traditionally seen as diligent. Japan consistently ranks among the most sleep-deprived OECD nations.