Learn Hardcore Japanese: yoru ni douga wo misugiru to, nemurenaikoto ga arimasu. - If I watch too many videos at night, sometimes I can’t sleep.

It’s often used for natural results or things that always / usually happen in that situation.
- 春になると、暖かくなります。
  When spring comes, it gets warm.
It feels more like “whenever A happens, B happens (as a natural consequence)” than a hypothetical “maybe” kind of if.

So here, it suggests: > Whenever I watch too many videos at night, the (usual) result is that sometimes I can’t sleep.

Why is it 夜に and not 夜は or just 夜?

夜に (yoru ni) is marking time with に, meaning “at night”.

に can mark a specific time point or time frame:
- 7時に起きます。 – I get up at 7.
- 夜に勉強します。 – I study at night.

Alternatives and nuance:

夜は動画を見すぎると、眠れないことがあります。
- 夜は adds a topic nuance:
  As for nighttime / At night (in general), if I watch too many videos, sometimes I can’t sleep.
- It slightly emphasizes “night” as the situation you’re talking about, like a contrast: During the day it’s fine, but at night…
夜、動画を見すぎると… (dropping に)
- In casual speech, Japanese often drops に with general times:
  - 明日学校に行きます → 明日、学校に行きます
- 夜、動画を見すぎると… is natural and common in spoken Japanese.

All of these are possible; 夜に is just the straightforward “at night” with the time marker に.

How does 見すぎる work? What exactly does ～すぎる mean?

見すぎる (mi-sugiru) is 見(る) + すぎる, literally “to do too much” of something.

Pattern:

Verb stem + すぎる
- 食べる → 食べすぎる – to eat too much
- 飲む → 飲みすぎる – to drink too much
- 見る → 見すぎる – to watch/look too much
You then conjugate すぎる like a regular る-verb:
- 見すぎます – polite
- 見すぎた – watched too much (past)
- 見すぎて – (and) watch too much

Nuance:

～すぎる usually has a negative nuance: “too much in a bad/undesirable way”.
So 動画を見すぎる = “to watch too many videos / to watch videos too much (excessively)”, implying this is not good (it causes sleep problems).

Why is 見すぎる in plain present tense, and あります polite? Is that okay?

Yes, this is a normal and correct combination.

Condition clause: 夜に動画を見すぎると
- Uses plain form (dictionary form) 見すぎる.
- In ～と, ～ば, ～たら conditional clauses, the verb is usually in plain form, even in otherwise polite sentences.
Main clause: 眠れないことがあります。
- Uses polite あります.

Mixed style is standard in this structure:

日本語がわからないと、困ることがあります。
If I don’t understand Japanese, there are times I have trouble.
Plain in the if-part, polite in the main part.

So the style here is consistent and natural.

What does 眠れないことがあります literally mean? Why not just 眠れません?

Literal breakdown:

眠れない – cannot sleep / be unable to sleep
こと – turns the verb phrase into a “thing” (a nominalizer)
があります – there is / there are

So literally:

眠れないことがあります。
There are times when “not being able to sleep” happens.

In natural English:
“Sometimes I can’t sleep.” / “There are times I can’t sleep.”

Why not 眠れません?

眠れません。 = I can’t sleep (right now / in this situation).
眠れないことがあります。 = There are occasions when I can’t sleep (as a general/habitual fact).

So ～ことがあります adds the meaning of “sometimes / at times”, rather than talking about only the present moment.

What is the role of こと here? Could I use の instead?

こと is a nominalizer: it turns the preceding phrase into a noun-like “thing”.

眠れない – cannot sleep
眠れないこと – the situation/occurrence of not being able to sleep

ことがあります is a very common pattern meaning:

Verb-plain + ことがある
→ There are times when (I) [verb]. / I sometimes [verb].

For example:

遅れることがあります。 – I’m sometimes late.
雨が急に降ることがあります。 – Sometimes it suddenly rains.

Could you use の?

眠れないのがある is not natural in this “sometimes” meaning.
With あります, this “sometimes I …” pattern is fixed as ことがあります.

You can say things like:

眠れないのはつらいです。 – The fact that I can’t sleep is hard.

Here の nominalizes, but that’s a different construction and meaning. For the “sometimes” pattern, stick with ことがあります.

Where is the subject “I” in this sentence? How do we know it’s “I” and not “you” or “people”?

Japanese often omits the subject when it’s clear from context.

In 夜に動画を見すぎると、眠れないことがあります。, there is no explicit subject, so it could be:

If *I watch too many videos at night, I sometimes can’t sleep.*
If *you watch too many videos at night, you sometimes can’t sleep.*
If *people watch too many videos at night, they sometimes can’t sleep.*

Which one is intended depends on:

Who is speaking
The conversation context
How the sentence is used (e.g., advice, personal story, general statement)

In a self-report context, it’s usually understood as “I”.
In more general advice (like in an article), it might be read as “people in general” or “you”.

Why is it 動画を and not 動画で or something else?

を marks the direct object of the verb 見る.

動画を見る – to watch videos
→ 動画 is what you see/watch, so it takes the object marker を.

Other particles would mean something else:

動画で – “by video / using video / in video form”
- 動画で説明します。 – I’ll explain it by video.
- Not correct for “watch videos”.

So here:

動画を見すぎる = to watch too many videos (to watch videos too much).
Keeping を is necessary to show that 動画 is the thing being watched.

Could I say 眠れなくなる instead of 眠れないことがあります? What’s the difference?

Yes, you can, but the nuance changes slightly.

眠れないことがあります。
- Pattern: Verb-ない + ことがあります
- Means: There are times when I cannot sleep → “sometimes I can’t sleep.”
- Emphasizes frequency / occasional occurrence.
眠れなくなる。
- 眠れる (can sleep) → 眠れなくなる (end up not being able to sleep; come to be unable to sleep).
- Emphasizes the change of state: “I become unable to sleep”.

So:

夜に動画を見すぎると、眠れなくなる。
= If I watch too many videos at night, I (end up) unable to sleep / I can’t fall asleep.
→ Focus on the resulting state.
夜に動画を見すぎると、眠れないことがあります。
→ Focus on: “Sometimes that leads to me not sleeping.” (not every single time, but there are such occasions).

Both are natural; the original sentence is hedged/softer, emphasizing “sometimes.”

Can I make this sentence more casual? How would a native say this to a friend?

A more casual version would drop some particles and use plain forms:

夜に動画見すぎると、眠れないことある。
Even more casual: 夜動画見すぎると、眠れなくなることある。

Changes:

Drop を after 動画 (common in speech):
動画を見すぎる → 動画見すぎる
Change あります → ある (plain)
～ことがあります → ～ことある
Possibly drop に: 夜に → 夜

All of these are natural among friends:

夜動画見すぎると、眠れなくなることあるよ。
If you watch too many videos at night, sometimes you can’t fall asleep, you know.

Can I move 夜に somewhere else in the sentence? Does the word order matter?

Yes, you can move 夜に as long as it stays in the first (conditional) clause. Word order within a clause is fairly flexible in Japanese.

Possible variations (all natural):

夜に動画を見すぎると、眠れないことがあります。
動画を夜に見すぎると、眠れないことがあります。
動画を見すぎると、夜に眠れないことがあります。
- This last one slightly shifts nuance to “I can’t sleep at night”.

Main points:

Elements marked by particles (に, を, が etc.) can usually be reordered without changing the core meaning much.
However, moving 夜に into the second clause (after the comma) changes what it modifies:
- 夜に眠れないことがあります。 = There are times I can’t sleep *at night.*

So yes, you can move it, but be aware of which verb it ends up modifying (watch vs. sleep).