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B1 adjective #5,500 most common 8 min read

寝不足の

Practice it Examples Notes & Tips 寝不足の in 30 Seconds
Explanation 寝不足の in your Level:
At the A1 level, learners are just beginning to grasp basic vocabulary. Terms related to immediate feelings or states, like being tired, might be introduced. However, specific adjectives like 'sleep-deprived' are likely too complex. A simple understanding of 'tired' (疲れた - tsukareta) would be the closest concept, but not directly addressing the cause of sleepiness.
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A2 learners can understand simple sentences and common phrases. They might encounter or learn basic words for feelings and states. The concept of 'sleepy' (眠い - nemui) would be accessible. While 'lack of sleep' (寝不足 - nebusoku) as a noun might be introduced, the adjective form 寝不足の (nebusoku no) is likely still beyond this level, as it requires understanding of adjective usage and more nuanced vocabulary.
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At the B1 level, learners can understand the main points of clear standard input on familiar matters. They can produce simple connected text on topics which are familiar or of personal interest. They are capable of using adjectives to describe states and conditions. Therefore, 寝不足の (nebusoku no) is appropriate for this level, as it describes a common, relatable state that affects daily life and performance. Learners at this stage can understand and use it to explain why they might be tired or unfocused.
B2 learners can understand the main ideas of complex text on both concrete and abstract topics. They can interact with a degree of fluency and spontaneity that makes regular interaction with native speakers quite possible. They can use precise vocabulary to describe states and conditions. 寝不足の is well within their grasp, and they can use it effectively in nuanced discussions about health, lifestyle, and the impact of sleep on productivity.
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C1 learners have a proficient command of the language. They can understand a wide range of demanding, longer texts, and recognize implicit meaning. They can express themselves fluently and spontaneously without much obvious searching for expressions. They can use the adjective 寝不足の accurately and appropriately in various contexts, including more formal or literary discussions about well-being and its impact on society.
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C2 learners have a near-native command of the language. They can understand virtually everything heard or read with ease. They can summarize information from different spoken and written sources, reconstructing arguments and accounts in a coherent presentation. For C2 learners, 寝不足の is a basic term, and they would likely use it effortlessly, perhaps even being aware of its etymology or subtle variations in usage compared to more formal terms like 睡眠不足.
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Practice it Examples Notes & Tips

寝不足の in 30 Seconds

  • Describes a state of not getting enough sleep.
  • Caused by insufficient rest.
  • Leads to tiredness and reduced focus.
  • Commonly used in everyday conversations about well-being.

Understanding 寝不足の (Nebusoku no)

The Japanese adjective 寝不足の (nebusoku no) is a straightforward and commonly used term to describe the state of being sleep-deprived. It literally means 'having a lack of sleep.' When someone is 寝不足の, they haven't had enough sleep, and this condition often manifests as fatigue, drowsiness, difficulty concentrating, and a general feeling of being unwell or less capable. It's a very relatable adjective because most people experience periods of insufficient sleep due to various reasons like work, study, stress, or illness.

Literal Meaning
Literally translates to 'of sleep deficiency' or 'related to lack of sleep.'
Common Usage Scenarios
People use 寝不足の to explain why they are feeling tired, irritable, or performing poorly. It's often used in casual conversations among friends, family, or colleagues. For instance, you might hear someone say they are 寝不足の because they stayed up late working on a project or had a restless night. It can also be used to describe someone else's appearance or demeanor if they seem particularly tired. The adjective form allows it to modify nouns like 'person' or 'feeling.'
Impact of Lack of Sleep
The consequences of being 寝不足の can range from mild inconvenience to significant impairment. This includes reduced alertness, slower reaction times, impaired judgment, and increased susceptibility to errors. In social situations, a person who is 寝不足の might appear less engaged or more prone to making mistakes in conversation or tasks. It's a common topic of discussion, especially in busy urban environments where long working hours are prevalent.

Example Sentence: 寝不足の顔をしているね。大丈夫？ (Nebusoku no kao o shite iru ne. Daijōbu?)

Translation: You have a sleep-deprived look. Are you okay?

Understanding this adjective is crucial for comprehending everyday conversations about well-being and productivity in Japan. It's a term that bridges the gap between physical state and social interaction.

Crafting Sentences with 寝不足の (Nebusoku no)

As an adjective, 寝不足の (nebusoku no) directly modifies nouns, describing them as being affected by a lack of sleep. It's often used to describe a person's appearance, their state of being, or their performance. Here are various ways to incorporate it into your Japanese sentences:

Modifying 'Person' or 'Appearance'
You can use 寝不足の to describe someone's face or overall look. For example, you might say someone looks tired because they are 寝不足の.
Describing a State of Being
It can describe one's condition or how they are feeling due to lack of sleep.
Explaining Performance or Behavior
The adjective can be used to explain why someone is not performing well or is acting a certain way, attributing it to sleep deprivation.
Combining with Other Expressions
It can be used with reasons (e.g., 〜のため - no tame) or to express a consequence.

Sentence: 昨夜は 寝不足の せいで、一日中眠かった。(Sakuyai wa nebusoku no sei de, ichinichijū nemukatta.)

Translation: Because of last night's lack of sleep, I was sleepy all day.

Sentence: 彼は 寝不足の 目をして会議に参加した。(Kare wa nebusoku no me o shite kaigi ni sankashita.)

Translation: He participated in the meeting with sleep-deprived eyes.

Sentence: 寝不足の 時は、判断力が鈍る。( Nebusoku no toki wa, handanryoku ga niburu.)

Translation: When sleep-deprived, judgment becomes dull.

Real-World Usage of 寝不足の (Nebusoku no)

The adjective 寝不足の (nebusoku no) is a frequent visitor in everyday Japanese conversations, reflecting the universal human experience of not getting enough sleep. You'll hear it in various settings, from casual chats among friends to more formal discussions about health and productivity.

Casual Conversations
Among friends and family, it's common to hear: 「昨日、遅くまで勉強したから、今日は寝不足の顔してるよ。」 (Kinō, osoku made benkyō shita kara, kyō wa nebusoku no kao shiteru yo.) - 'I studied late last night, so I have a sleep-deprived look today.' This is a very natural way to explain one's appearance.
Workplace Discussions
In professional settings, especially in Japan where overwork can be a concern, people might use it to explain a dip in performance or an inability to focus: 「すみません、寝不足のせいで、ミスをしてしまいました。」 (Sumimasen, nebusoku no sei de, misu o shite shimaimashita.) - 'I'm sorry, because of my lack of sleep, I made a mistake.'
Media and Health Discussions
News reports, health articles, and discussions about lifestyle often refer to the negative effects of insufficient sleep. You might see headlines or phrases like: 「寝不足の現代人」 (Nebusoku no gendaijin) - 'Sleep-deprived modern people,' highlighting societal issues related to sleep.
Personal Reflection
When journaling or talking about personal well-being, someone might reflect: 「最近、寝不足の日が続いているので、体調が優れない。」 (Saikin, nebusoku no hi ga tsuzuite iru node, taichō ga sugurenai.) - 'Lately, I've been having consecutive sleep-deprived days, so my physical condition isn't good.'

Common Phrase: 寝不足の状態 (Nebusoku no jōtai)

Meaning: A state of sleep deprivation.

Avoiding Pitfalls with 寝不足の (Nebusoku no)

While 寝不足の (nebusoku no) is a common and useful adjective, learners might make a few mistakes when using it. Understanding these common errors can help you use the word more accurately and naturally.

Confusing with the Noun
Mistake: Using 寝不足 (nebusoku) directly as an adjective modifying a noun. For example, saying 「寝不足の人」 (nebusoku no hito) instead of the correct 「寝不足の人」 (nebusoku no hito) when describing a person who is sleep-deprived. While understandable, it's grammatically incorrect for the adjective form.
Incorrect Placement
Mistake: Placing 寝不足の after the noun it modifies without a connecting particle or copula. For instance, saying 「顔、寝不足のです。」 (Kao, nebusoku no desu.) This sounds unnatural. The correct way is either 「寝不足の顔です。」 (Nebusoku no kao desu.) or 「顔が寝不足です。」 (Kao ga nebusoku desu.)
Overusing or Underusing
Mistake: Sometimes learners might avoid using it altogether, opting for more general terms like 'tired' (疲れた - tsukareta) even when the specific cause is lack of sleep. Conversely, overusing it for minor tiredness might sound like complaining. It's best used when the lack of sleep is a significant factor.
Misinterpreting Nuance
Mistake: Thinking that 寝不足の is a permanent state or a serious illness. It generally refers to a temporary condition resulting from insufficient sleep over a short period. For chronic sleep disorders, other terms might be more appropriate.

Incorrect: 私は寝不足の気分です。(Watashi wa nebusoku no kibun desu.)

Correct: 私は寝不足です。(Watashi wa nebusoku desu.) or 私は寝不足のせいで気分が悪いです。(Watashi wa nebusoku no sei de kibun ga warui desu.)

Exploring Synonyms and Alternatives for 寝不足の (Nebusoku no)

While 寝不足の (nebusoku no) is a direct and common way to express sleep deprivation, Japanese offers several other words and phrases that convey similar meanings or nuances. Understanding these alternatives can enrich your vocabulary and allow for more precise expression.

Noun: 寝不足 (Nebusoku)
This is the noun form, meaning 'lack of sleep.' It's used as the subject or object of a sentence, or to explain a cause. Example: 「寝不足で仕事になりません。」 (Nebusoku de shigoto ni narimasen.) - 'I can't get any work done due to lack of sleep.' This is the root from which the adjective is formed.
Adjective: 眠い (Nemui)
This is a very common i-adjective meaning 'sleepy.' While often a consequence of being 寝不足の, 眠い focuses on the feeling of wanting to sleep, whereas 寝不足の describes the state of having not slept enough. You can be 眠い for reasons other than lack of sleep (e.g., after a heavy meal). Example: 「あくびが止まらない。とても眠い。」 (Akubi ga tomaranai. Totemo nemui.) - 'I can't stop yawning. I'm very sleepy.'
Phrase: 睡眠不足 (Suimin busoku)
This is a more formal or technical term for 'lack of sleep,' often used in medical or scientific contexts. It functions as a noun. Example: 「慢性的な睡眠不足は健康に悪影響を与える。」 (Manseiteki na suimin busoku wa kenkō ni akueikyō o ataeru.) - 'Chronic lack of sleep negatively affects health.' While similar to 寝不足, 睡眠不足 sounds more formal.
Phrase: 疲れている (Tsukarete iru)
This means 'to be tired' or 'to be exhausted.' It's a general term that can encompass tiredness from lack of sleep, overwork, physical exertion, or illness. If you are 寝不足の, you are likely also 疲れている, but 疲れている doesn't necessarily imply lack of sleep. Example: 「今日は一日中歩き回ったので、とても疲れている。」 (Kyō wa ichinichijū arukimawatta node, totemo tsukarete iru.) - 'I walked around all day today, so I'm very tired.'
Adverbial Phrase: 眠い目をこする (Nemui me o kosuru)
This phrase means 'to rub one's sleepy eyes.' It's a physical action associated with being sleepy, often a direct result of being 寝不足の. Example: 「朝、眠い目をこすりながら会社に向かった。」 (Asa, nemui me o kosurinagara kaisha ni mukatta.) - 'In the morning, I headed to work while rubbing my sleepy eyes.'

Comparison: 寝不足の (Nebusoku no) vs. 眠い (Nemui)

寝不足の describes the cause (lack of sleep), while 眠い describes the symptom (feeling sleepy). You can be 眠い without being 寝不足の, but being 寝不足の almost always makes you 眠い.

How Formal Is It?

Fun Fact

The character '寝' (ne) for sleep is associated with the act of lying down. The character '足' (soku) in '不足' (fusoku) means 'foot' or 'leg,' but in this context, it comes from the verb '足りる' (tariru - to be enough) and its negative form '足りない' (tarinai - not enough), hence 'lack.'

Pronunciation Guide

UK /ne̞bɯso̞kɯ no̞/
US /ne̞bɯso̞kɯ no̞/
ne-BU-so-ku no
Rhymes With
sokono tobusoku yokusoku kankei nai shōtai būtsu kūtsu tsukusu
Common Errors
  • Pronouncing 'bu' too strongly or adding an extra vowel sound.
  • Incorrectly stressing the syllables, making it sound unnatural.
  • Mispreading the syllables, leading to confusion with other words.

Difficulty Rating

Reading 3/5

The adjective form is straightforward and its meaning is directly tied to the noun 'lack of sleep.' Understanding its usage in modifying nouns is key. Texts discussing health, daily life, or personal feelings will frequently use this term.

Writing 3/5

Learners need to correctly place the adjective before the noun it modifies and understand the context where it's appropriate. Distinguishing it from the noun form and other related adjectives like 'nemui' is important.

Speaking 3/5

It's a very common term for explaining one's state of tiredness due to lack of sleep. Practicing its use in everyday conversation, like explaining why one is unfocused or looks tired, is beneficial.

Listening 3/5

Native speakers use this term frequently, so recognizing it in conversations about well-being, work, or daily life is essential for comprehension.

What to Learn Next

Prerequisites

寝る (neru) 眠い (nemui) 疲れた (tsukareta) 不足 (fusoku) 顔 (kao)

Learn Next

睡眠不足 (suimin busoku) 徹夜 (tetsuya) 夜更かし (yofukashi) 休息 (kyūsoku) 健康 (kenkō)

Advanced

不眠症 (fuminshō) 慢性化 (manseika) 恒常性 (kōjōsei) 認知機能 (ninchi kinō) ウェルビーイング (werubīingu)

Grammar to Know

Na-adjectives and the particle の

Many adjectives in Japanese function like na-adjectives. When they modify a noun, they take the particle の (no) before the noun. For example, 'beautiful person' is きれいな人 (kirei na hito), but if we consider a noun like 'lack of sleep' (寝不足 - nebusoku) and want to make it an adjective, we use 寝不足の (nebusoku no) to modify another noun, like 寝不足の人 (nebusoku no hito - sleep-deprived person).

Using 〜のせいで (no sei de) to express cause

This phrase is used to indicate the cause of a negative outcome. For example, 'Because of lack of sleep, I made a mistake.' -> 寝不足のせいで、ミスをした。(Nebusoku no sei de, misu o shita.)

Using 〜時 (toki) to indicate 'when'

This is used to specify a time or condition. For example, 'When sleep-deprived...' -> 寝不足の時… (Nebusoku no toki...)

Using 〜気味 (gimi) to indicate 'somewhat' or 'tendency'

This suffix is attached to nouns to express a slight degree or tendency. For example, 'somewhat sleep-deprived' -> 寝不足気味 (nebusoku gimi).

Using 〜ようだ (yō da) for supposition or appearance

This is used to express 'seems like' or 'appears to be.' For example, 'He seems sleep-deprived.' -> 彼は寝不足のようだ。(Kare wa nebusoku no yō da.)

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Examples by Level

1

昨夜はよく眠れなかったので、今日は寝不足のせいで集中できない。

Last night I couldn't sleep well, so today I can't concentrate because of lack of sleep.

「〜のせいで」 (no sei de) means 'because of' and often carries a slightly negative connotation, suitable for explaining the cause of a problem.

2

彼は寝不足の顔で会議に来た。

He came to the meeting with a sleep-deprived face.

「〜の顔」 (no kao) means 'face of ~'. Here, it's used to describe the appearance caused by lack of sleep.

3

寝不足の時は、気分がすぐれないことが多い。

When sleep-deprived, my mood is often not good.

「気分がすぐれない」 (kibun ga sugurenai) means 'not feeling well' or 'in low spirits'.

4

週末はゆっくり寝て、寝不足を解消したい。

I want to sleep soundly on the weekend and resolve my sleep deprivation.

「〜を解消したい」 (o kaishō shitai) means 'want to resolve/eliminate'.

5

長時間の運転は、寝不足だと危険だ。

Driving for a long time is dangerous when sleep-deprived.

「〜だと」 (da to) means 'when it is ~' or 'if it is ~'.

6

子供は寝不足のせいで、機嫌が悪くなりがちだ。

Children tend to become ill-tempered due to lack of sleep.

「〜くなりがちだ」 (ku narigachi da) means 'tend to become ~'.

7

寝不足のせいで、頭がぼーっとしている。

My head feels fuzzy due to lack of sleep.

「頭がぼーっとしている」 (atama ga bōtto shite iru) means 'head is fuzzy/dazed'.

8

試験前は、寝不足の学生が多い。

There are many sleep-deprived students before exams.

Simple descriptive sentence using the adjective.

1

慢性的な寝不足は、集中力や記憶力の低下を招く。

Chronic sleep deprivation leads to a decline in concentration and memory.

「〜を招く」 (o maneku) means 'to invite/cause/lead to'.

2

彼女は寝不足のせいか、最近少しやつれているように見える。

Perhaps because she's sleep-deprived, she looks a bit worn out recently.

「〜せいか」 (sei ka) suggests a possibility or speculation.

3

寝不足の状態で運転することは、飲酒運転と同等に危険である。

Driving while sleep-deprived is as dangerous as driving under the influence of alcohol.

「〜と同等に」 (to dōtō ni) means 'equally to' or 'on par with'.

4

十分な睡眠をとることは、寝不足の解消に不可欠だ。

Getting enough sleep is essential for resolving sleep deprivation.

「不可欠だ」 (fukaketsu da) means 'essential' or 'indispensable'.

5

彼は寝不足のせいで、普段ならしないようなミスを犯した。

Due to lack of sleep, he made a mistake he wouldn't normally make.

「〜ないような」 (nai yō na) means 'like ~ that one doesn't do'.

6

寝不足の人は、感情のコントロールが難しくなる傾向がある。

Sleep-deprived people tend to have difficulty controlling their emotions.

「〜傾向がある」 (keikō ga aru) means 'there is a tendency to'.

7

このプロジェクトは、寝不足のチームメンバーたちによって進められた。

This project was carried out by the sleep-deprived team members.

Passive voice construction used to describe the state of the members.

8

寝不足のとき、甘いものへの欲求が高まるのはよく知られている。

It is well-known that cravings for sweets increase when sleep-deprived.

「〜への欲求が高まる」 (e no yokkyū ga takamaru) means 'desire for ~ increases'.

1

現代社会における寝不足の蔓延は、公衆衛生上の深刻な課題となっている。

The prevalence of sleep deprivation in modern society has become a serious public health issue.

「蔓延」 (man'en) means 'prevalence' or 'spread,' and 「公衆衛生上の課題」 (kōshū eisei-jō no kadai) means 'public health issue'.

2

彼は、寝不足のせいで思考が散漫になりがちだという自己分析を報告した。

He reported a self-analysis that his thoughts tend to become scattered due to lack of sleep.

「思考が散漫になる」 (shikō ga sanman ni naru) means 'thoughts become scattered.' 「自己分析」 (jiko bunseki) is 'self-analysis'.

3

寝不足のパフォーマンスへの影響は、単なる眠気にとどまらず、判断力や創造性にも及びうる。

The impact of sleep deprivation on performance extends beyond mere sleepiness, potentially affecting judgment and creativity.

「〜にとどまらず」 (ni todomarazu) means 'not limited to.' 「及びうる」 (oyobiuru) means 'can extend to'.

4

長引く寝不足は、身体の恒常性を脅かす。

Prolonged sleep deprivation threatens the body's homeostasis.

「長引く」 (nagabiku) means 'prolonged' or 'long-lasting.' 「恒常性」 (kōjōsei) is 'homeostasis'.

5

この状況下では、寝不足の個人がリスクの高い判断を下す可能性が高まる。

Under these circumstances, the likelihood of sleep-deprived individuals making high-risk judgments increases.

「リスクの高い判断」 (risuku no takai handan) means 'high-risk judgment.'

6

彼は、寝不足のせいで本来の能力を発揮できずにいることを嘆いた。

He lamented that he couldn't demonstrate his true abilities due to lack of sleep.

「嘆く」 (nageku) means 'to lament' or 'to grieve.' 「本来の能力」 (honrai no nōryoku) is 'original/true ability'.

7

寝不足の経験は、しばしば人生の岐路における決断の質に影響を与える。

Experiences of sleep deprivation often influence the quality of decisions at life's crossroads.

「人生の岐路」 (jinsei no kiro) means 'crossroads of life.'

8

その研究は、寝不足が学習効率に与える負の影響を定量的に示した。

The study quantitatively demonstrated the negative impact of sleep deprivation on learning efficiency.

「学習効率」 (gakushū kōritsu) is 'learning efficiency.' 「定量的に示す」 (teiryōteki ni shimesu) means 'to show quantitatively'.

1

現代社会における寝不足の慢性化は、個人のウェルビーイングのみならず、社会全体の生産性にも看過できない影響を及ぼしている。

The chronicization of sleep deprivation in modern society has a considerable impact not only on individual well-being but also on the overall productivity of society.

「慢性化」 (manseika) is 'chronicization.' 「看過できない」 (kanka dekinai) means 'cannot be overlooked.' 「及ぼしている」 (oyoboshite iru) means 'is exerting/having an effect.'

2

彼は、寝不足による認知機能の低下を、自らの体験的認識を基盤として詳細に論じた。

He discussed in detail the decline in cognitive function due to sleep deprivation, based on his own experiential perception.

「認知機能」 (ninchi kinō) is 'cognitive function.' 「体験的認識」 (taikenteki ninshiki) is 'experiential perception.'

3

寝不足の個人が陥りやすい、判断の誤謬やリスク認知の歪みは、集団意思決定の場においても無視できない。

The errors in judgment and distortions in risk perception that sleep-deprived individuals are prone to fall into cannot be ignored, even in group decision-making settings.

「陥りやすい」 (ochiiriyasui) means 'prone to fall into.' 「誤謬」 (gobyū) is 'fallacy' or 'error.' 「歪み」 (yugami) is 'distortion.'

4

その研究は、寝不足がもたらす生理学的・心理学的影響の複雑な相互作用を解明しようと試みた。

The study attempted to elucidate the complex interactions of physiological and psychological effects brought about by sleep deprivation.

「もたらす」 (motarasu) means 'to bring about.' 「解明しようと試みた」 (kaimei shiyō to kokoromita) means 'attempted to elucidate/clarify.'

5

長期間にわたる寝不足は、神経系の可塑性を変化させ、長期的な健康問題の素因となりうる。

Prolonged sleep deprivation can alter the plasticity of the nervous system and become a predisposing factor for long-term health problems.

「神経系」 (shinkeikei) is 'nervous system.' 「可塑性」 (kasosei) is 'plasticity.' 「素因」 (soin) is 'predisposing factor.'

6

彼は、寝不足という個人的な困難を乗り越え、驚異的な業績を達成した。

He overcame the personal hardship of sleep deprivation and achieved remarkable results.

「乗り越え」 (norikoe) means 'overcome.' 「驚異的な業績」 (kyōiteki na gyōseki) is 'remarkable achievement.'

7

寝不足の経験から得た洞察は、人間行動の理解を深める上で貴重な示唆を与える。

Insights gained from the experience of sleep deprivation offer valuable suggestions for deepening the understanding of human behavior.

「洞察」 (dōsatsu) is 'insight.' 「示唆を与える」 (shisa o ataeru) means 'to give suggestion/implication.'

8

その作家は、寝不足の夜にインスピレーションを得たと語り、作品にその影響を反映させている。

The author stated that they gained inspiration on sleepless nights and reflected that influence in their work.

「インスピレーションを得た」 (insupirēshon o eta) means 'gained inspiration.' 「反映させている」 (han'ei sasete iru) means 'is reflecting.'

Common Collocations

寝不足の顔 (nebusoku no kao)
寝不足のせいで (nebusoku no sei de)
寝不足の状態 (nebusoku no jōtai)
寝不足気味 (nebusoku gimi)
寝不足の目 (nebusoku no me)
寝不足解消 (nebusoku kaishō)
寝不足の悪影響 (nebusoku no akueikyō)
寝不足の時 (nebusoku no toki)
寝不足の体 (nebusoku no karada)
寝不足のストレス (nebusoku no sutoresu)

Common Phrases

寝不足です。

— I am sleep-deprived.

すみません、今日は寝不足です。(Sumimasen, kyō wa nebusoku desu.) - Excuse me, I am sleep-deprived today.

寝不足のせいで〜

— Because of lack of sleep, ~

寝不足のせいで、集中できません。(Nebusoku no sei de, shūchū dekimasen.) - Because of lack of sleep, I can't concentrate.

寝不足の顔をしている。

— To have a sleep-deprived look.

あなたは寝不足の顔をしているね。(Anata wa nebusoku no kao o shite iru ne.) - You have a sleep-deprived look.

寝不足を解消する。

— To resolve/relieve sleep deprivation.

週末は寝不足を解消したい。(Shūmatsu wa nebusoku o kaishō shitai.) - I want to relieve my sleep deprivation on the weekend.

寝不足気味だ。

— To feel somewhat sleep-deprived.

最近、寝不足気味です。(Saikin, nebusoku gimi desu.) - Lately, I've been feeling somewhat sleep-deprived.

寝不足で頭が痛い。

— My head hurts due to lack of sleep.

昨夜は全然眠れず、寝不足で頭が痛い。(Sakuyai wa zenzen nemurezu, nebusoku de atama ga itai.) - I couldn't sleep at all last night, and my head hurts from lack of sleep.

寝不足の人は〜

— Sleep-deprived people ~

寝不足の人は、イライラしやすい。(Nebusoku no hito wa, iraira shiyasui.) - Sleep-deprived people tend to get irritated easily.

寝不足の時こそ〜

— Precisely when sleep-deprived, ~

寝不足の時こそ、バランスの取れた食事を心がけるべきだ。(Nebusoku no toki koso, baransu no toreta shokuji o kokorogakeru beki da.) - Precisely when sleep-deprived, one should aim for a balanced diet.

寝不足による影響

— Effects caused by lack of sleep.

寝不足による影響は様々だ。(Nebusoku ni yoru eikyō wa samazama da.) - The effects caused by lack of sleep are various.

寝不足のまま

— Remaining sleep-deprived / Without having slept enough

寝不足のまま仕事に行くのはつらい。(Nebusoku no mama shigoto ni iku no wa tsurai.) - It's tough to go to work while remaining sleep-deprived.

Often Confused With

寝不足の vs 眠い (nemui)

While often a symptom of being 寝不足の, 眠い (nemui) simply means 'sleepy' and can be caused by many factors other than lack of sleep. 寝不足の specifically points to the insufficient sleep itself as the cause.

寝不足の vs 疲れている (tsukarete iru)

This means 'tired' or 'exhausted' and is a general state. One can be 疲れている from physical exertion, illness, or emotional stress, not just lack of sleep. 寝不足の is a more specific reason for feeling tired.

寝不足の vs 睡眠不足 (suimin busoku)

This is the noun form meaning 'lack of sleep.' 寝不足の is the adjective form used to describe something or someone as being affected by this lack of sleep. You can't say 'I am 睡眠不足' directly; you would say 'I am 寝不足です' (Nebusoku desu) or 'I have 睡眠不足' (Suimin busoku ga arimasu).

Easily Confused

寝不足の vs 眠い (nemui)

Both terms relate to sleepiness and tiredness.

眠い (nemui) describes the feeling of wanting to sleep, which is a symptom. 寝不足の (nebusoku no) describes the state of not having slept enough, which is often the cause of feeling 眠い. You can be 眠い for reasons other than lack of sleep (e.g., after a heavy meal), but if you are 寝不足の, you are almost certainly 眠い.

寝不足のせいで眠い。(Nebusoku no sei de nemui.) - I'm sleepy because of lack of sleep.

寝不足の vs 疲れている (tsukarete iru)

Both terms indicate a lack of energy or a state of being worn out.

疲れている (tsukarete iru) is a general term for being tired, which can result from many factors like physical activity, stress, or illness. 寝不足の (nebusoku no) specifically refers to tiredness caused by insufficient sleep. You can be 疲れている without being 寝不足の, but being 寝不足の almost always leads to feeling 疲れている.

昨夜は徹夜したので、とても疲れているし、寝不足の顔をしている。(Sakuyai wa tetsuya shita node, totemo tsukarete iru shi, nebusoku no kao o shite iru.) - I stayed up all night, so I'm very tired and have a sleep-deprived look.

寝不足の vs 睡眠不足 (suimin busoku)

They are closely related in meaning and origin.

睡眠不足 (suimin busoku) is the noun 'lack of sleep,' often used in more formal or medical contexts. 寝不足の (nebusoku no) is the adjective form derived from the more colloquial noun 寝不足 (nebusoku), used to directly modify nouns (e.g., 'sleep-deprived person'). You would say 'I have 睡眠不足' (Suimin busoku ga arimasu) or 'I am 寝不足' (Nebusoku desu), but you would say 'a 寝不足の person' (nebusoku no hito).

睡眠不足は健康に良くない。寝不足の人は注意が必要だ。(Suimin busoku wa kenkō ni yoku nai. Nebusoku no hito wa chūi ga hitsuyō da.) - Lack of sleep is not good for health. Sleep-deprived people need to be careful.

寝不足の vs 徹夜 (tetsuya)

Both relate to not sleeping.

徹夜 (tetsuya) means 'staying up all night,' implying a deliberate action or circumstance that prevents sleep for an entire night. 寝不足の (nebusoku no) describes the resulting state of having not slept enough, which could be due to 徹夜, but also due to fragmented sleep, short sleep, or other disruptions. 徹夜 is an event, while 寝不足の is a state.

徹夜したせいで、ひどい寝不足だ。(Tetsuya shita sei de, hidoi nebusoku da.) - Because I stayed up all night, I'm severely sleep-deprived.

寝不足の vs 夜更かし (yofukashi)

Both involve staying up late and can lead to lack of sleep.

夜更かし (yofukashi) means 'staying up late,' often for leisure or non-essential activities. It's the act of keeping late hours. 寝不足の (nebusoku no) describes the resulting condition of not getting enough sleep. While 夜更かし can lead to being 寝不足の, one can be 寝不足の without necessarily having stayed up late (e.g., due to noise, illness, or early morning commitments).

夜更かしが習慣になって、寝不足の毎日だ。(Yofukashi ga shūkan ni natte, nebusoku no mainichi da.) - Staying up late has become a habit, and I'm sleep-deprived every day.

Sentence Patterns

B1

寝不足のせいで、[結果]。

寝不足のせいで、仕事がはかどらない。(Nebusoku no sei de, shigoto ga hakadoranai.) - Due to lack of sleep, work is not progressing.

B1

[人]は寝不足の顔をしている。

彼は寝不足の顔をしている。(Kare wa nebusoku no kao o shite iru.) - He has a sleep-deprived look.

B1

寝不足の時、[状態]。

寝不足の時、集中力が低下する。(Nebusoku no toki, shūchūryoku ga teika suru.) - When sleep-deprived, concentration decreases.

B2

長引く寝不足は、[悪影響]。

長引く寝不足は、健康を害する。(Nagabiku nebusoku wa, kenkō o gaisuru.) - Prolonged lack of sleep harms health.

B2

[原因]で、寝不足の[状態]になった。

夜更かしで、寝不足の状態になった。(Yofukashi de, nebusoku no jōtai ni natta.) - Due to staying up late, I entered a state of sleep deprivation.

B2

寝不足の[人]は、[特徴]。

寝不足の人は、イライラしやすい。(Nebusoku no hito wa, iraira shiyasui.) - Sleep-deprived people tend to get irritated easily.

C1

寝不足の蔓延は、[社会的問題]。

寝不足の蔓延は、社会全体の生産性を低下させる。(Nebusoku no man'en wa, shakai zentai no seisansē o teika saseru.) - The prevalence of sleep deprivation lowers the productivity of society as a whole.

C1

寝不足による[影響]は、[重要性]。

寝不足による認知機能の低下は、見過ごせない問題だ。(Nebusoku ni yoru ninchi kinō no teika wa, misuginotenai mondai da.) - The decline in cognitive function due to sleep deprivation is a problem that cannot be overlooked.

Word Family

Nouns

寝不足 (nebusoku) lack of sleep
睡眠 (suimin) sleep
不眠 (fumin) insomnia

Verbs

寝る (neru) to sleep
眠る (nemuru) to sleep (more formal/poetic)
眠る (nemuru) to sleep (more formal/poetic)

Adjectives

寝不足の (nebusoku no) sleep-deprived
眠い (nemui) sleepy
疲れた (tsukareta) tired

Related

睡眠不足 (suimin busoku) lack of sleep (formal)
徹夜 (tetsuya) staying up all night
夜更かし (yofukashi) staying up late
休息 (kyūsoku) rest
回復 (kaifuku) recovery
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How to Use It

frequency

High

Common Mistakes
  • Using 寝不足 (nebusoku) directly as an adjective. → 寝不足の人 (nebusoku no hito)

    寝不足 (nebusoku) is a noun. To modify another noun, you need the particle の (no), making it 寝不足の (nebusoku no). Saying 寝不足の人 sounds unnatural; the correct form is 寝不足の人.

  • Incorrect placement of the adjective. → 寝不足の顔をしている。(Nebusoku no kao o shite iru.)

    The adjective 寝不足の should precede the noun it modifies. Saying 顔が寝不足をしている (Kao ga nebusoku o shite iru) is grammatically incorrect and nonsensical. The correct structure is 'sleep-deprived face'.

  • Confusing 寝不足の with 眠い (nemui). → 寝不足のせいで眠い。(Nebusoku no sei de nemui.)

    眠い (nemui) means 'sleepy.' 寝不足の (nebusoku no) means 'sleep-deprived.' While often related, they are not interchangeable. You can be 眠い for reasons other than lack of sleep, but being 寝不足の implies a lack of sleep as the cause.

  • Using 寝不足 (nebusoku) as a verb. → 寝不足です。(Nebusoku desu.) or 寝不足になっている。(Nebusoku ni natte iru.)

    寝不足 (nebusoku) is a noun. It cannot directly function as a verb. To express the state of being sleep-deprived, you use the copula です (desu) or the verb になる (ni naru) to indicate a change of state.

  • Overusing the phrase to complain. → Use it factually to explain a situation.

    While common, constantly complaining about being 寝不足の might be perceived negatively. It's best used to explain a specific instance or reason for tiredness rather than as a constant lament.

Tips

Adjective Placement

Remember that 寝不足の (nebusoku no) is an adjective. It typically comes before the noun it modifies, like in 寝不足の顔 (nebusoku no kao - sleep-deprived face) or 寝不足の人 (nebusoku no hito - sleep-deprived person).

Noun vs. Adjective

Distinguish between the noun 寝不足 (nebusoku - lack of sleep) and the adjective 寝不足の (nebusoku no - sleep-deprived). You 'have' 寝不足 (nebusoku ga aru) or you 'are' 寝不足 (nebusoku desu), but you describe someone as 寝不足の (nebusoku no).

Explaining Tiredness

This is a perfect phrase to use when you want to explain why you're feeling tired, unfocused, or grumpy. It's a common and relatable reason.

Related Terms

Expand your vocabulary by learning related terms like 眠い (nemui - sleepy), 疲れた (tsukareta - tired), and 徹夜 (tetsuya - staying up all night) to better describe states of tiredness and their causes.

Syllable Stress

Focus on pronouncing each syllable clearly: ne-bu-so-ku no. While there isn't heavy stress, ensuring each part is audible helps with comprehension.

Mnemonic Devices

Use memory aids like associating 'nebusoku no' with 'neck-bust-so-cool, no!' to help recall the word and its meaning.

Cultural Nuance

Be mindful of the cultural context. While common, directly commenting on someone's 'sleep-deprived look' might require a close relationship or a gentle tone.

Sentence Building

Construct sentences using 寝不足の in various contexts: explaining your own feelings, describing someone else, or discussing the effects of lack of sleep.

Using 〜のせいで

Practice using 寝不足の with phrases like 〜のせいで (no sei de) to explain negative consequences, such as '寝不足のせいで、集中できません。(Nebusoku no sei de, shūchū dekimasen.) - Because of lack of sleep, I can't concentrate.'

Distinguishing from Nemui

Understand the difference between being 眠い (nemui - sleepy) and being 寝不足の (nebusoku no - sleep-deprived). The former is a feeling, the latter is the cause.

Memorize It

Mnemonic

Imagine a person who is so sleep-deprived (寝不足の - nebusoku no) that their 'ne'ck is bent over, they 'bu'st into tears from exhaustion, they can't 'so'undly sleep, and they're 'ku'mbly looking. The 'no' at the end signifies the adjective form.

Visual Association

Picture a clock with very little time left before morning, and a person tossing and turning in bed with wide, tired eyes. The clock face could be partially obscured, emphasizing the 'lack' of sleep time. The 'nebusoku no' phrase could be written around the image.

Word Web

寝不足の (nebusoku no) - Sleep-deprived 眠い (nemui) - Sleepy 疲れた (tsukareta) - Tired 睡眠不足 (suimin busoku) - Lack of sleep (formal) 徹夜 (tetsuya) - All-nighter 夜更かし (yofukashi) - Staying up late 元気がない (genki ga nai) - Lacking energy 集中できない (shūchū dekinai) - Can't concentrate

Challenge

Try to describe your own state or someone else's using 寝不足の (nebusoku no) in a sentence. For example, 'I am 寝不足の today because I watched a movie late last night.' Or, 'My friend looks 寝不足の because they have a big exam tomorrow.'

Word Origin

The term is a compound word formed from the noun 寝不足 (nebusoku) and the possessive/adjectival particle の (no). 寝不足 itself is composed of 寝る (neru - to sleep) and 不足 (fusoku - lack, deficiency).

Original meaning: Literally, 'of lack of sleep.' The particle 'no' transforms the noun phrase 'lack of sleep' into an adjective that describes something or someone as being affected by that lack.

Japonic

Cultural Context

The term itself is neutral and descriptive. However, in certain contexts, complaining excessively about being 寝不足の might be perceived as unprofessional or lacking in commitment, especially in environments that highly value hard work. It's generally used as a factual explanation for one's state.

In English-speaking cultures, 'sleep-deprived' is also a common term used to describe someone who hasn't slept enough. The reasons and consequences are universally understood. Phrases like 'I'm running on fumes' or 'I'm exhausted' are common alternatives.

In anime and manga, characters often exhibit extreme fatigue or fall asleep suddenly due to lack of sleep, visually representing the state of being 寝不足の. Discussions about work culture in Japan often touch upon the prevalence of long hours and the resulting sleep deprivation, making 寝不足 a relevant term in social commentary. Health and wellness campaigns in Japan frequently highlight the importance of sleep and the negative impacts of being 寝不足の on physical and mental health.

Practice in Real Life

Real-World Contexts

Explaining one's tiredness or lack of focus.

  • 寝不足のせいで、集中できない。(Nebusoku no sei de, shūchū dekinai.)
  • 今日は寝不足の顔をしている。(Kyō wa nebusoku no kao o shite iru.)
  • 寝不足で頭が痛い。(Nebusoku de atama ga itai.)

Discussing health and well-being.

  • 寝不足は体に悪い。(Nebusoku wa karada ni warui.)
  • 寝不足を解消したい。(Nebusoku o kaishō shitai.)
  • 寝不足の悪影響。(Nebusoku no akueikyō.)

Describing someone else's appearance or state.

  • 彼は寝不足のようだ。(Kare wa nebusoku no yō da.)
  • 彼女は寝不足の目つきをしている。(Kanojo wa nebusoku no metsuki o shite iru.)
  • 寝不足気味かな？(Nebusoku gimi ka na?)

Talking about reasons for poor performance or mistakes.

  • 寝不足のせいでミスをした。(Nebusoku no sei de misu o shita.)
  • 寝不足の時は判断力が鈍る。(Nebusoku no toki wa handanryoku ga niburu.)
  • 寝不足でパフォーマンスが落ちた。(Nebusoku de pafōmansu ga ochita.)

General observations about lifestyle.

  • 最近、寝不足の人が多い。(Saikin, nebusoku no hito ga ōi.)
  • 寝不足の生活は避けたい。(Nebusoku no seikatsu wa saketai.)
  • 寝不足の経験から学んだ。(Nebusoku no keiken kara mananda.)

Conversation Starters

"最近、よく眠れていますか？私は寝不足気味で困っています。"

"昨夜は遅くまで起きていたので、今日は寝不足の顔をしています。大丈夫ですか？"

"寝不足のせいで、仕事に集中できません。何か良い対策はありますか？"

"試験前はいつも寝不足になります。皆さんはどうですか？"

"寝不足の時、どんな症状が出やすいですか？私はいらいらしてしまいます。"

Journal Prompts

今日の私の体調はどうですか？寝不足を感じますか？具体的な症状を書き出してみましょう。

最近、睡眠不足の原因は何だと思いますか？仕事、勉強、それとも他の理由でしょうか？

寝不足によって、私の日常生活や気分にどのような影響が出ていますか？

もし寝不足を解消できるとしたら、どんなことをしてみたいですか？

過去に経験したひどい寝不足の時のエピソードを思い出して、その時の状況や感情を書き留めてみましょう。

Frequently Asked Questions

10 questions

Both mean 'lack of sleep.' 寝不足 (nebusoku) is the more common, everyday term. 睡眠不足 (suimin busoku) is more formal and often used in medical or academic contexts. As adjectives, 寝不足の (nebusoku no) is used to describe a state, while you would typically say you 'have' 睡眠不足 (suimin busoku ga arimasu).

No, 寝不足の (nebusoku no) is used to describe people or their states/appearances. You cannot say 'a sleep-deprived car' or 'a sleep-deprived building.' It pertains to living beings that require sleep.

You can say: 私はとても寝不足です。(Watashi wa totemo nebusoku desu.) or ひどい寝不足です。(Hidoi nebusoku desu.) If you want to use the adjective form to describe yourself, you might say something like: 私は寝不足の状態です。(Watashi wa nebusoku no jōtai desu.)

Yes, generally it implies a negative state of fatigue and reduced function. It's used to explain why someone might be feeling unwell, unfocused, or making mistakes.

Connect 'nebusoku' to 'neck-bust-so-cool' as a mnemonic, emphasizing the feeling of extreme tiredness. Remember the 'no' particle turns it into an adjective describing a person or their features.

Yes, you can. For example, 寝不足の子供は機嫌が悪くなりがちだ。(Nebusoku no kodomo wa kigen ga waruku narigachi da.) - Sleep-deprived children tend to become ill-tempered.

Yes, absolutely. 寝不足の refers to any amount of sleep that is insufficient for your body's needs, not necessarily zero sleep. If you slept only 3-4 hours when you need 7-8, you are 寝不足の.

眠い (nemui) means 'sleepy' and describes the feeling of wanting to sleep. 寝不足の (nebusoku no) means 'sleep-deprived' and describes the state of having not slept enough, which is often the cause of feeling 眠い. You can be 眠い for other reasons, but if you are 寝不足の, you will likely feel 眠い.

It can be sensitive depending on the context and your relationship with the person. Directly saying 'You look 寝不足の' might be perceived as critical. It's often safer to say something like 'Are you okay? You seem a little tired.' or use it more subtly, like '寝不足の顔をしているね' (You have a sleep-deprived look) which can be a gentle observation.

You would use 睡眠不足 (suimin busoku) in more formal settings, like academic papers, medical reports, or serious discussions about health. For example, 'The study investigated the effects of 睡眠不足 on cognitive function.' In everyday conversation, 寝不足 is more common.

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