Hello, I’m Kodak.
If you watch anime, talk with Japanese friends, or read casual Japanese messages, you will often see the short expression:
眠い。
Nemui.
I’m sleepy.
眠い (nemui) is the most common Japanese word for feeling sleepy or wanting to fall asleep.
However, learners often confuse it with 疲れた (tsukareta: tired), 眠たい (nemutai: sleepy), 寝たい (netai: want to sleep), and だるい (darui: sluggish).
① what 眠い (nemui) means
② how to pronounce and write it
③ why it is an い-adjective, not a verb
④ how to conjugate it naturally
⑤ common sentence patterns such as 眠くなる and 眠くて
⑥ the differences between 眠い, 疲れた, 眠たい, 寝たい, だるい, and 眠そう
⑦ natural conversational and anime-style examples
⑧ the history and kanji structure of the word
Today’s Japanese word is 眠い (nemui)!
Its core image is “sleep is pulling you toward it.”
That is why 眠い means “sleepy,” “drowsy,” or “I feel like sleeping.”
What Does 眠い (Nemui) Mean?
眠い means that you feel sleepiness and are likely to fall asleep.
⇒ sleepy
⇒ drowsy
⇒ feeling like sleeping
⇒ “I’m sleepy.”
眠い。
Nemui.
I’m sleepy.
今日はすごく眠い。
Kyō wa sugoku nemui.
I’m really sleepy today.
授業中、ずっと眠かった。
Jugyō-chū, zutto nemukatta.
I was sleepy throughout the class.
Sometimes English speakers say “I’m tired” when they really mean “I need sleep.” Japanese usually separates the two ideas:
眠い ⇒ sleepy
疲れた ⇒ physically or mentally tired
Pronunciation and Writing of 眠い
Hiragana: ねむい
Katakana: ネムイ
Romaji: nemui
Mora: ね・む・い (3 morae)
Pronounce each mora clearly:
ね (ne) + む (mu) + い (i)
The final い is part of the adjective and should not be omitted.
In normal adult writing, both 眠い and ねむい are natural. Katakana ネムイ may be used in manga, social media, advertising, or stylized writing for emphasis.
眠い Is an い-Adjective
眠い is an い-adjective. It directly describes a sleepy condition, so it conjugates by changing the final い.
眠くない — not sleepy
眠かった — was sleepy
眠くなかった — was not sleepy
眠くて — sleepy, and… / because I was sleepy…
眠ければ — if you are sleepy
眠すぎる — too sleepy
Present: 眠い
今、眠い。
Ima, nemui.
I’m sleepy now.
Negative: 眠くない
まだ眠くない。
Mada nemukunai.
I’m not sleepy yet.
Past: 眠かった
昨日は一日中眠かった。
Kinō wa ichinichijū nemukatta.
I was sleepy all day yesterday.
Polite: 眠いです
少し眠いです。
Sukoshi nemui desu.
I’m a little sleepy.
Because 眠い is an い-adjective, do not replace its final い with です. The natural polite form is 眠いです, not 眠です.
How to Use 眠い in Japanese
1. 眠い: “I’m Sleepy”
Japanese often omits the subject when it is obvious.
眠い。
Nemui.
I’m sleepy.
You do not usually need to say 私は unless you are contrasting yourself with someone else.
眠い。Possible, but more explicit:
私は眠い。
2. とても／すごく／めっちゃ眠い: “Very Sleepy”
今日はとても眠いです。
Kyō wa totemo nemui desu.
I’m very sleepy today.
めっちゃ眠い。
Meccha nemui.
I’m super sleepy.
めっちゃ is very casual. とても is neutral and works in polite speech.
3. ～て眠い: “Sleepy Because…”
A reason can be connected with the te-form.
昨日あまり寝ていなくて眠い。
Kinō amari nete inakute nemui.
I’m sleepy because I didn’t sleep much last night.
朝が早くて眠い。
Asa ga hayakute nemui.
I’m sleepy because I had to get up early.
4. ～ので／から眠い: “Sleepy Because…”
寝不足だから眠い。
Nebusoku da kara nemui.
I’m sleepy because I haven’t had enough sleep.
薬を飲んだので眠いです。
Kusuri o nonda node nemui desu.
I’m sleepy because I took medicine.
5. 眠くなる: “To Become Sleepy”
To turn an い-adjective into “become …,” change い to く and add なる.
↓ い → く
眠くなる
⇒ become sleepy / start feeling sleepy
ご飯を食べると眠くなる。
Gohan o taberu to nemuku naru.
I get sleepy after eating.
この音楽を聞くと眠くなります。
Kono ongaku o kiku to nemuku narimasu.
This music makes me sleepy.
6. 眠くて～: “I’m So Sleepy That…”
眠くて集中できない。
Nemukute shūchū dekinai.
I’m too sleepy to concentrate.
眠くて目が開かない。
Nemukute me ga akanai.
I’m so sleepy that I can’t keep my eyes open.
7. 眠そう: “Looks Sleepy”
Use 眠そう when you are judging someone’s appearance rather than directly stating their inner feeling.
眠そうだね。
Nemusō da ne.
You look sleepy.
彼はとても眠そうだった。
Kare wa totemo nemusō datta.
He looked very sleepy.
Useful Expressions with 眠い
I’m unbearably sleepy.眠くてたまらない
I’m so sleepy I can’t stand it.
眠くなってきた
I’m starting to get sleepy.
眠気がする
I feel sleepy. (less common than 眠い)
眠気を感じる
to feel drowsiness
眠気を覚ます
to shake off sleepiness / wake oneself up
眠い目をこする
to rub one’s sleepy eyes
眠すぎる
too sleepy / unbelievably sleepy
眠い vs 疲れた: Sleepy vs Tired
This is the most important distinction for English speakers.
Your body wants sleep.
⇒ sleepy / drowsy疲れた (tsukareta)
Your physical or mental energy has been used up.
⇒ tired / exhausted
That is why direct translation can be confusing. Ask yourself what you actually feel:
Do your eyes feel heavy and you may fall asleep? ⇒ 眠い
Have you used up your energy after work or exercise? ⇒ 疲れた
Compare the difference in context
昨日三時間しか寝ていないから眠い。
I only slept for three hours last night, so I’m sleepy.
⇒ Your body wants sleep.
一日中働いて疲れた。
I’m tired after working all day.
⇒ Your energy has been used up.
疲れたし、眠い。
I’m tired and sleepy.
⇒ Both feelings can exist at the same time.
For a full explanation, see What Does 疲れた (Tsukareta) Mean?
眠い vs 眠たい: What Is the Difference?
眠い and 眠たい both mean “sleepy.” In many sentences, they are interchangeable.
The most neutral and widely useful form.眠たい
Also means sleepy; it may sound slightly more conversational, expressive, or childlike in some contexts and regions.
今日は眠い。
I’m sleepy today.
今日は眠たい。
I’m sleepy today.
The difference is usually much smaller than learners expect. If you are unsure, use 眠い.
眠い vs 寝たい: Sleepy vs Want to Sleep
You feel sleepiness.
⇒ I’m sleepy.寝たい (netai)
You want to perform the action of sleeping or going to bed.
⇒ I want to sleep / I want to go to bed.
眠いけど、まだ寝たくない。
Nemui kedo, mada netakunai.
I’m sleepy, but I don’t want to go to bed yet.
疲れたから早く寝たい。
Tsukareta kara hayaku netai.
I’m tired, so I want to go to bed early.
眠い is a physical feeling. 寝たい is a desire or intention.
眠い vs だるい: Sleepy vs Sluggish
だるい describes physical heaviness, sluggishness, or lack of energy. A person can feel だるい without being close to falling asleep.
My body wants sleep.だるい
My body feels heavy and I do not want to move.
眠くはないけど、体がだるい。
Nemuku wa nai kedo, karada ga darui.
I’m not sleepy, but my body feels sluggish.
寝不足で眠いし、体もだるい。
Nebusoku de nemui shi, karada mo darui.
I’m sleepy from lack of sleep, and my body feels sluggish too.
眠い vs 眠そう: Feeling Sleepy vs Looking Sleepy
The speaker directly describes their own feeling.眠そう
The speaker judges from another person’s appearance.
⇒ looks sleepy
私は眠い。
I’m sleepy.
彼は眠そうだ。
He looks sleepy.
Because you cannot directly experience another person’s inner state, 眠そう is often more natural when describing what you observe.
眠い vs うとうとする: Sleepy vs Dozing Off
うとうとする describes lightly falling asleep or repeatedly drifting between wakefulness and sleep.
You feel sleepy but may still be awake.うとうとする
You begin to doze lightly.
眠くて、電車の中でうとうとしていた。
Nemukute, densha no naka de utouto shite ita.
I was sleepy and kept dozing off on the train.
Common Casual and Anime-Style Uses of 眠い
In casual conversation, anime, manga, games, and social media, 眠い frequently appears as a complete sentence.
I’m sleepy…ねむっ！
So sleepy! / I’m exhausted with sleepiness!
マジで眠い。
I’m seriously sleepy.
もう無理。眠い。
I can’t do this anymore. I’m sleepy.
眠くなってきた。
I’m starting to get sleepy.
眠すぎて頭が回らない。
I’m too sleepy to think straight.
寝落ちしそう。
I feel like I’m about to fall asleep unexpectedly.
Natural Example Sentences with 眠い
朝早く起きたから眠い。
Asa hayaku okita kara nemui.
I’m sleepy because I woke up early.
コーヒーを飲んでもまだ眠い。
Kōhī o nonde mo mada nemui.
I’m still sleepy even after drinking coffee.
お昼ご飯の後は眠くなる。
Ohiru-gohan no ato wa nemuku naru.
I get sleepy after lunch.
眠かったら、少し休んだほうがいいよ。
Nemukattara, sukoshi yasunda hō ga ii yo.
If you’re sleepy, you should rest for a while.
彼は眠そうにあくびをした。
Kare wa nemusō ni akubi o shita.
He yawned sleepily.
眠くて、勉強に集中できなかった。
Nemukute, benkyō ni shūchū dekinakatta.
I was too sleepy to concentrate on studying.
もう夜中の二時だよ。眠くないの？
Mō yonaka no ni-ji da yo. Nemukunai no?
It’s already two in the morning. Aren’t you sleepy?
今日は全然眠くない。
Kyō wa zenzen nemukunai.
I’m not sleepy at all today.
眠すぎて、電車を乗り過ごした。
Nemusugite, densha o norisugoshita.
I was so sleepy that I missed my stop.
眠いなら、先に寝ていいよ。
Nemui nara, saki ni nete ii yo.
If you’re sleepy, you can go to bed first.
Example Dialogue Using 眠い
Situation 1: The morning after staying up late
A: おはよう。眠そうだね。
Ohayō. Nemusō da ne.
Morning. You look sleepy.
B: うん。昨日、三時まで起きてたから眠い。
Un. Kinō, san-ji made okiteta kara nemui.
Yeah. I’m sleepy because I stayed up until three last night.
⇒ A observes the appearance with 眠そう. B directly describes the feeling with 眠い.
Situation 2: After a long day
A: 大丈夫？
Daijōbu?
Are you okay?
B: 疲れたし、眠い。今日はもう寝る。
Tsukareta shi, nemui. Kyō wa mō neru.
I’m tired and sleepy. I’m going to bed now.
⇒ 疲れた describes low energy. 眠い describes the urge to sleep.
Situation 3: During a lecture
A: この授業、どう？
Kono jugyō, dō?
How is this class?
B: 先生の声を聞いてると眠くなる。
Sensei no koe o kiiteru to nemuku naru.
Listening to the teacher’s voice makes me sleepy.
⇒ 眠くなる describes the change into a sleepy state.
Common Mistakes with 眠い
Mistake 1: Using 眠る to Mean “I’m Sleepy”
I sleep / I will sleep.○ 私は眠い。
I’m sleepy.
眠る is a verb meaning “to sleep.” 眠い is an adjective describing sleepiness.
Mistake 2: Confusing 眠い and 寝たい
I feel sleepy.寝たい
I want to sleep.
Mistake 3: Saying 眠くです
× 眠くです。
○ 眠いです。
I’m sleepy.
眠く is the adverbial form used before verbs such as なる: 眠くなる.
Mistake 4: Directly Stating Another Person’s Inner Feeling
彼は眠い。
He is sleepy.Often more natural from appearance alone:
彼は眠そうだ。
He looks sleepy.
Mistake 5: Translating Every English “Tired” as 疲れた
When English “tired” means you might fall asleep, Japanese 眠い may be the better translation.
I’m tired. I’m going to bed.
Depending on the intended feeling:
眠いから寝る。
I’m sleepy, so I’m going to bed.
The Origin and History of 眠い
Modern 眠い comes from the older Japanese adjective ねむし. Japanese dictionaries record the literary form ねむし and historical examples of the later spoken form from the late Muromachi period.
Historical development
Older literary adjective: ねむし
↓
Spoken Japanese developed the modern adjective form
↓
Modern Japanese: 眠い (ねむい)
The exact deeper origin of the sound sequence ねむ- is not established clearly enough to state with certainty. For learners, the most useful connection is the word family:
眠る (nemuru) — to sleep
眠り (nemuri) — sleep
眠気 (nemuke) — sleepiness / drowsiness
睡眠 (suimin) — sleep
The Kanji 眠: Eye + Phonetic Element
The kanji 眠 is a phonetic-semantic character.
eye民
primarily supplies the historical sound element in this character
目 + 民 = 眠
to sleep / sleepy / sleep
Related Japanese Sleep Words
to sleep / go to bed / lie down眠る (nemuru)
to sleep; often focuses more on the state of sleep
眠気 (nemuke)
sleepiness / drowsiness
寝不足 (nebusoku)
lack of sleep / insufficient sleep
居眠りする (inemuri suru)
to doze while sitting, such as in class or on a train
うたた寝する (utatane suru)
to fall asleep unintentionally for a short time
うとうとする (utouto suru)
to doze lightly
寝落ちする (neochi suru)
to unintentionally fall asleep while doing something
FAQ About 眠い
What does nemui mean in Japanese?
眠い (nemui) means “sleepy,” “drowsy,” or “feeling like sleeping.”
How do you say “I’m sleepy” in Japanese?
The most natural casual expression is simply 眠い (nemui). A polite form is 眠いです (nemui desu).
Is nemui an adjective or a verb?
眠い is an い-adjective. The verb “to sleep” is 寝る or 眠る.
What is the difference between nemui and tsukareta?
眠い means sleepy and describes the desire or tendency to fall asleep. 疲れた means tired and describes depleted physical or mental energy.
What is the difference between nemui and nemutai?
Both 眠い and 眠たい mean sleepy and are often interchangeable. 眠い is the safest neutral choice, while 眠たい can sound more conversational or expressive depending on the speaker and region.
What is the difference between nemui and netai?
眠い means “I feel sleepy.” 寝たい means “I want to sleep” or “I want to go to bed.”
How do you say “You look sleepy” in Japanese?
Say 眠そうだね (nemusō da ne) casually or 眠そうですね (nemusō desu ne) politely.
How do you say “I’m getting sleepy” in Japanese?
Say 眠くなってきた (nemuku natte kita). It describes sleepiness gradually beginning to affect you.
What does nemukute mean?
眠くて is the te-form of 眠い. It connects sleepiness to a result, as in 眠くて集中できない, “I’m too sleepy to concentrate.”
What does nemusō mean?
眠そう means “looks sleepy.” It describes an impression based on someone’s appearance or behavior.
Can I write nemui in hiragana?
Yes. ねむい is completely natural. The kanji spelling is 眠い.
What does nemui mean in anime?
It has the same basic meaning: “I’m sleepy.” Anime characters may use shortened or emphatic forms such as ねむっ, マジで眠い, or 眠くなってきた.
Is 眠い rude?
No. It is a neutral everyday adjective. However, saying it repeatedly during a meeting or class could sound inattentive depending on the situation.
What is the noun form of 眠い?
眠気 (nemuke) means sleepiness or drowsiness, and 眠さ (nemusa) means the degree or feeling of being sleepy.
Is お疲れ様 related to 眠い?
Not directly. 眠い describes sleepiness. お疲れ様 is a conventional expression that acknowledges another person’s work or effort. See What Does お疲れ様 (Otsukaresama) Mean?
Summary: The Meaning and Usage of 眠い
眠い means “sleepy,” “drowsy,” or “feeling like sleeping.”● Writing
Kanji: 眠い
Hiragana: ねむい
Romaji: nemui
● Grammar
眠い is an い-adjective.
眠くない = not sleepy
眠かった = was sleepy
眠くなる = become sleepy
眠くて = sleepy, and / because one is sleepy
眠そう = looks sleepy
● Key differences
眠い = sleepy
疲れた = tired
眠たい = also sleepy; largely interchangeable
寝たい = want to sleep
だるい = sluggish / physically heavy
眠そう = looks sleepy
● Core image
Sleep is pulling you toward it.
Remember the simplest contrast:
眠い ⇒ “My body wants sleep.”
疲れた ⇒ “My energy has been used up.”
寝たい ⇒ “I want to go to bed.”
Once you separate the feeling, condition, and desire, these Japanese expressions become much easier to use naturally!
References
- Kotobank: 眠い — definition, literary form, historical examples, and derived words.
- Kotobank: 眠たい — definition and relationship to 眠い.
- Kotobank: 眠気 — definition of sleepiness and drowsiness.
- Kotobank: 寝る — meanings including sleeping, going to bed, and lying down.
- Kotobank: 居眠り.
- Kotobank: うたた寝.
- Kanjipedia: 眠 — readings, meanings, and kanji formation.