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N4Lesson notes · Sep 30, 2026

Jet lag in Japanese: 時差ボケじさぼけ, and the other things Japanese can be ボケ about

Jet lag in Japanese is 時差ボケじさぼけ (jisaboke) — literally "time difference" plus "fogginess" — and that same ボケ shows up in a whole family of words for feeling out of sync.

Most learners meet 時差ボケじさぼけ as a travel phrase and stop there. But the second half, ボケ, is worth a closer look. It turns up in words about sleep, holidays, peace, and even Japanese stand-up comedy — and in one usage it can be genuinely rude. Once you see what ボケ means, a dozen words stop being separate things to memorize.

The basics

How do you say "jet lag" in Japanese?

You say 時差ボケじさぼけ (jisaboke). It is a compound of two words: 時差じさ (jisa, "time difference") and ボケ (boke, "dullness, haziness, being out of focus"). It is often written with hiragana too, as 時差じさぼけ. Same word, same meaning.

時差ボケじさぼけで眠ねむいです。 — I'm sleepy because of jet lag. (polite, the all-purpose travel sentence) まだ時差ボケじさぼけが治なおらない。 — I still haven't got over my jet lag. (casual, talking to a friend or host)

You will also hear katakana ジェットラグ, borrowed straight from English, and people will understand it. But 時差ボケじさぼけ is the everyday word, and it is the one you should reach for first.

What is 時差じさ, on its own?

時差じさ (jisa) means "time difference" between two places, and it is a plain noun. You do not say "I have 時差じさ" to mean you are jet-lagged — that is the most common slip, and we come back to it below. On its own, 時差じさ is just the gap in the clocks.

日本にほんとは8時間じかんの時差じさがあります。 — There is an eight-hour time difference with Japan. (polite, the number changes with where you live) 時差じさはどのくらいですか。 — How big is the time difference? (polite, asking about a destination)

Notice the verb: 時差じさがある — "there is a time difference." It works like weather or distance. If you need to talk about the clock times themselves, how to tell time in Japanese covers the numbers you will need.

How do you say you have it, or that it is bad?

Use 時差ボケじさぼけ with が and one of a few natural verbs or adjectives. The pattern is the same as for a cold or a headache: the problem is the subject.

時差ボケじさぼけがひどいです。 — My jet lag is terrible. (polite; ひどい = awful, severe) 時差ボケじさぼけで朝起あさおきられなかった。 — I couldn't get up in the morning because of jet lag. (casual past) 時差ボケじさぼけを治なおしたいです。 — I want to get rid of my jet lag. (polite; 治なおす = to cure, to heal)

The particle で marks the cause: 時差ボケじさぼけで眠ねむい means "sleepy because of jet lag." That single で does a lot of work in travel conversations.

What does ボケ actually mean?

ボケ comes from the verb ぼける, meaning to go blurry, dull, or hazy. A photo can be ぼけている (out of focus). A mind can be ぼけている (foggy, not sharp). It is the sense of "the edges have gone soft."

That picture explains 時差ボケじさぼけ nicely: your body clock and the local clock are out of sync, so everything feels slightly out of focus. It is also why the same syllable turns up in the next section.

Beyond the basics

What is 寝ねぼける?

寝ねぼける (nebokeru) means to be groggy and half-asleep right after waking, not fully aware of what you are doing. The 寝ね is "sleep" and ぼける is our hazy verb again.

寝ねぼけてた。ごめん。 — I was half asleep. Sorry. (casual, after saying something odd on waking) 寝ねぼけた顔かおをしているね。 — You look half asleep. (casual, teasing a friend at breakfast)

Jet-lagged travelers do this a lot in real life, so it is a very useful word to recognize when a host jokes about it.

Which other things can be ボケ?

Any long stretch that dulls your routine can get a ボケ label. Japanese happily attaches it to a cause, and the result names the foggy feeling that follows.

Word Reading Meaning Feel
時差ボケじさぼけ jisaboke jet lag everyday, travel
寝ねぼけ / 寝ねぼける nebokeru groggy right after waking everyday, light
休やすみボケ yasumiboke sluggish after time off casual, common
正月しょうがつボケ shōgatsuboke sluggish after the New Year holidays seasonal, casual
平和へいわボケ heiwaboke complacent from long peace slightly critical, opinion
ボケ (comedy) boke the "silly one" in a comedy duo neutral, entertainment

The word 休やすみボケ is the one to steal for your own use. After a long weekend or holiday, you can say:

連休れんきゅうのあとで、休やすみボケしてる。 — I'm in a post-holiday fog. (casual, the day back at work or school) 正月しょうがつボケがまだ抜ぬけない。 — I still haven't shaken off the New Year slump. (casual; 抜ぬける = to come out of, to wear off)

平和へいわボケ is different in tone. It describes a society or a person so used to peace and safety that they have stopped paying attention to risks. It is usually a mild criticism, and you will see it in news commentary and debates rather than small talk.

平和へいわボケしていると言いわれても仕方しかたがない。 — You can't argue if people say we've gone soft from peace. (fairly formal, opinion)

What is ボケ in comedy, and why is it in so many anime?

In Japanese comedy, the ボケ is the person who says the silly or off-target thing; the ツッコミ is the person who snaps back with a correction. The pair together is the basic engine of manzai (漫才まんざい), the Japanese two-person stand-up format.

ボケとツッコミのコンビ — a comedy duo of a "silly one" and a "straight one" (neutral, a phrase you will hear on TV) なんでやねん! — Why would you do that?! (Kansai-style ツッコミ line, said in a sharp comic tone)

Comedy anime lean on this heavily. One character says something absurd, and another slaps a quick retort on it. If you hear ボケる in this context, it means "to play the silly one" or "to make a joke that is deliberately off." The word is the same ぼける root, but in comedy it means "to say something off-target on purpose."

Is there a ボケ you should not use?

Yes — ボケる or ボケた used about an older person's memory is old-fashioned and disrespectful. In the past, people used it for age-related memory loss. Today it is considered rude, and the more careful word for the medical condition is 認知にんち症しょう (ninchishō (ninchish). As a learner, the safest rule is simple: do not say ボケた about a real person's mind.

おじいちゃん、ボケたの? — Grandpa, have you gone senile? (do NOT say this — rude even in a family joke)

You may still hear ボケ used this way in older dramas or from older speakers, so it is worth understanding. But you should not use it yourself. When you mean "half asleep", say 寝ねぼけてる. When you mean "jet lag", say 時差ボケじさぼけ. Those are the safe ones.

How do you talk about being tired, not just foggy?

時差ボケじさぼけ names the cause; 眠ねむい and だるい describe how you feel. Combine them and you get the natural sentences travelers actually use.

時差ボケじさぼけで、頭あたまがぼーっとします。 — With the jet lag, my head is in a haze. (polite; ぼーっと = spaced out) 時差ボケじさぼけでだるいです。 — I feel sluggish from jet lag. (polite; だるい = heavy, drained) 眠ねむいけど、夜よるは眠ねむれない。 — I'm sleepy, but I can't sleep at night. (casual, the classic jet-lag pattern)

For a fuller list of words to describe tiredness — 疲つかれた, 眠ねむい, ヘトヘト and more — see Japanese words for tired, which sorts them by how you actually feel.

Talking to a Japanese friend or host: a short model conversation

In real conversation, the answer to "are you okay?" is usually 時差ボケじさぼけです plus a small plan. Here is a realistic exchange between a traveler and a host, with the sentences kept short and natural.

A:おはよう。よく眠ねむれた? — Morning. Did you sleep well? (casual, host) B:あまり…。まだ時差ボケじさぼけが治なおらなくて。 — Not really... I still haven't got over my jet lag. (polite-casual; 〜なくて trails off softly) A:今日きょうは無理むりしないで、ゆっくりしてね。 — Don't push yourself today; take it easy. (casual, caring)

Notice how B does not say a full sentence. 治なおらなくて… just fades out, and the host fills in the rest. That soft trailing-off is very natural in Japanese.

What if you are getting ready before a trip?

You can describe your prep with 早はやく寝ねる (go to bed early) and 対策たいさく (taisaku, "countermeasures"). This is a small, practical phrase pair worth knowing.

来日前らいにちまえに早はやく寝ねて、時差ボケじさぼけ対策たいさくをしました。 — Before coming to Japan I went to bed early as a jet-lag countermeasure. (polite, a sentence you can say on arrival)

The verb する pairs with 対策たいさく to mean "take measures against something." It also works for other problems: 風邪かぜ対策たいさく (cold measures), 暑あつさ対策たいさく (heat measures). If your trip is for work rather than leisure, business trip in Japanese: 出張しゅっちょう has the words for that kind of travel.

"Still" and "already": how do you say it hasn't gone away?

まだ means "still," and it is the word that makes 時差ボケじさぼけ sound like an ongoing problem. In the sentence まだ時差ボケじさぼけが治なおらない, まだ paired with a negative verb means "still not." If you are unsure how まだ and もう behave, already and still in Japanese: もう and まだ sorts out the pairs.

もう時差ボケじさぼけは大丈夫だいじょうぶです。 — My jet lag is already fine. (polite; もう = already) まだ少すこし時差ボケじさぼけです。 — I still have a bit of jet lag. (polite; まだ = still)

Common mistakes

  • Saying 時差じさがある to mean "I am jet-lagged." 時差じさがある just means "there is a time difference." For your own condition, say 時差ボケじさぼけです. Compare: 日本にほんとは時差じさがあります (a fact about two places) versus 時差ボケじさぼけです (how you feel).
  • Dropping the ボケ. 時差じさで眠ねむい is understandable, but 時差ボケじさぼけで眠ねむい is the usual way to name the condition.
  • Using ボケる about an older person. As covered above, this is rude. Use 寝ねぼけてる for "half asleep," and avoid the word for real people's memory.
  • Using 直なおす for a body condition. 時差ボケじさぼけ is a condition, so use 治なおる (it clears up) or 治なおす (to cure it): まだ時差ボケじさぼけが治なおらない.
  • Reading ボケ only as comedy. In a travel conversation, 時差ボケじさぼけ is never a joke. It is just a physical state, so the comedy ボケ has nothing to do with it apart from the shared root.

Practice

Build each answer before opening it. Questions 5 and 6 are a pair: same syllable, very different worlds.

1. Say "I'm sleepy because of jet lag."

Show answer

時差ボケじさぼけで眠ねむいです — the particle で marks the cause: jet lag is why you are sleepy.

2. What are the two parts of 時差ボケじさぼけ?

Show answer

時差じさ (time difference) + ボケ (fogginess, dullness) — the body clock and the local clock are out of sync, so everything feels out of focus.

3. "There is an eight-hour time difference with Japan." Which noun and verb do you use?

Show answer

日本にほんとは8時間じかんの時差じさがあります — 時差じさ is a plain noun for the gap between places, and it takes ある.

4. What is wrong with saying 時差じさがあります to mean "I have jet lag"?

Show answer

時差じさ alone is only "time difference," not a personal state. To say you are jet-lagged, use 時差ボケじさぼけです.

5. Which word describes being groggy right after waking up?

Show answer

寝ねぼける — 寝ね (sleep) plus the hazy verb ぼける. 寝ねぼけてる means "I'm half asleep."

6. In manzai, who is the ボケ and who is the ツッコミ?

Show answer

The ボケ says the silly, off-target thing; the ツッコミ snaps back with the correction. Together they run the joke. The word comes from the same ぼける root, but it is a different job from 時差ボケじさぼけ.

7. After a long holiday you feel sluggish. Which "〜ボケ" word fits?

Show answer

休やすみボケ — 連休れんきゅうのあとで休やすみボケしてる. At New Year the seasonal version is 正月しょうがつボケ.

8. What does 平和へいわボケ describe, and what is its tone?

Show answer

Being complacent because peace has lasted so long. It is a mild criticism, common in news and opinion rather than small talk.

9. Why should you avoid saying ボケた about an older person's memory?

Show answer

It is an old-fashioned, disrespectful word. The careful term for the condition is 認知にんち症しょう. Use 寝ねぼけてる for "half asleep" and 時差ボケじさぼけ for jet lag instead.

10. Say "I still haven't got over my jet lag" in casual Japanese.

Show answer

まだ時差ボケじさぼけが治なおらない — まだ with a negative verb means "still not," which is exactly the ongoing feeling you want.

With a teacher in a trial lesson, describe your own 時差ボケじさぼけ, or a 休やすみボケ after a holiday, and try 寝ねぼける for the morning after.

FAQ

Is 時差ボケじさぼけ a formal word or a casual one? It is neutral. You can say 時差ボケじさぼけです to a teacher, a host, or a hotel front desk, and 時差ボケじさぼけで眠ねむい to a friend. It does not need any softening.

Can I write 時差じさぼけ in hiragana? Yes. 時差ボケじさぼけ and 時差じさぼけ are both used, they read the same, and they mean the same. Pick either and stay consistent.

Is ジェットラグ wrong? No. It is understood and you will sometimes see it in articles or on airline pages. But in conversation, 時差ボケじさぼけ is what most people say, so it sounds more natural.

What is the difference between 眠ねむい and 時差ボケじさぼけ? 眠ねむい describes the feeling of being sleepy, which can have any cause. 時差ボケじさぼけ names one specific cause: crossing time zones. You can combine them: 時差ボケじさぼけで眠ねむい.

Are ボケ and ぼける the same word? They are the same root. ぼける is the verb ("to go blurry or dull"), and ボケ is the noun form. In compounds like 休やすみボケ, it is the noun that gets attached to a cause.

Do I always need で after 時差ボケじさぼけ? No. で marks a cause (時差ボケじさぼけで眠ねむい). If you are just stating the problem, use が: 時差ボケじさぼけがひどい. Both patterns are natural, and choosing between them is about whether you are giving a reason or describing the state.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

時差ボケ	じさボケ — jet lag
時差	じさ — time difference
ボケ	ボケ — fogginess; the "silly one" in comedy
ぼける	ぼける — to go blurry or dull
寝ぼける	ねぼける — to be groggy, half-asleep after waking
休みボケ	やすみボケ — post-holiday sluggishness
正月ボケ	しょうがつボケ — post-New-Year sluggishness
平和ボケ	へいわボケ — complacency from long peace
ツッコミ	ツッコミ — the "straight one" who corrects the joke
漫才	まんざい — manzai, two-person comedy
認知症	にんちしょう — dementia (the respectful term)
ひどい	ひどい — awful, severe
直す	なおす — to fix, to correct
治す	なおす — to cure, to heal
治る	なおる — to get over, to heal
眠い	ねむい — sleepy
だるい	だるい — sluggish, heavy
対策	たいさく — countermeasure
まだ	まだ — still, yet
もう	もう — already

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime, so most of the example sentences on this blog come from lines I've actually heard students ask about — including 時差ボケじさぼけ, a word that tends to come up right before a trip to Japan. For practice with feedback, Book a trial lesson · $13, or work through Japanese practice exercises first.

Sources: the author's own lessons and standard reference grammars.

More drills like the ones above, plus a timed JLPT-style mock test: Practice · N4 · Read something at this level: JLPT N4 stories with audio

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