Если тебе не спится, прочитай книгу или послушай музыку в наушниках.

They are close in meaning, but not the same.

• ты не спишь = you are not sleeping (simple factual statement about what you are doing/not doing).
• тебе не спится = literally it doesn’t sleep to you → you can’t sleep / you don’t feel like sleeping / sleep won’t come.

тебе не спится is:

• more about the state/feeling (sleep just isn’t happening),
• often used for insomnia or restlessness,
• neutral and very natural in this context.

In advice like this (what to do when you can’t fall asleep), тебе не спится sounds more idiomatic than ты не спишь.

спится comes from спать (to sleep).

• Person/number: 3rd person singular
• Tense: present
• Aspect: imperfective
• Type: impersonal (no real subject like he/she/it)

The -ся is a reflexive ending, but here it doesn’t mean oneself; it’s used to form impersonal verbs that describe states or feelings:

• мне не сидится – I can’t sit still / don’t feel like sitting
• ей хорошо работается – she works well / it’s easy for her to work
• ему не верится – he can’t believe it

So спится is an impersonal reflexive form: it sleeps, in the sense sleep happens (or, with не, doesn’t happen).

With these impersonal state verbs (спится, работается, верится, дышится etc.), the experiencer (the person who experiences the state) is put in the dative.

Patterns:

• Мне не спится. – I can’t sleep.
• Ему хорошо работается. – He works easily.
• Нам здесь не сидится. – We don’t feel like sitting here.

So тебе не спится = to you, it doesn’t sleep → you can’t sleep.

That’s why it’s тебе (dative), not ты (nominative) or тебя (accusative/genitive).

Yes, you can; it’s correct and natural:

• Если ты не можешь заснуть, прочитай книгу...

Nuance:

• тебе не спится – more emotional/idiomatic, focuses on the general state: you’re lying there and sleep just doesn’t come.
• ты не можешь заснуть – more literal: you cannot fall asleep (you are trying but fail).

In everyday speech, both are common. тебе не спится sounds slightly softer and more colloquial/idiomatic in this context.

Russian normally uses a comma between:

• a subordinate clause introduced by если (if) and
• the main clause with the consequence/result.

Structure here:

• Если тебе не спится – subordinate conditional clause
• прочитай книгу или послушай музыку в наушниках – main clause (what to do in that situation)

Rule: subordinate clause + main clause → comma between them:

• Если будет дождь, останемся дома.
• Если у тебя есть время, позвони мне.

In Russian, the choice of aspect in the imperative changes the nuance:

• прочитай (from прочитать, perfective) – read (a book) once / from start to finish / as a completed action.
• послушай (from послушать, perfective) – listen (for a while) / have a listen as a bounded action.

Here, the speaker suggests a specific, goal-oriented action as a remedy or solution: Do X (once) to help you fall asleep → perfective is natural.

Using imperfective:

• читай книгу – (keep) reading a book (focus on the ongoing process, like a standing instruction or habit).
• слушай музыку – (keep) listening to music.

So:

• Если тебе не спится, прочитай книгу... – suggestion: try this one action.
• Если тебе не спится, читай книгу... – sounds more like a general rule/habit: “whenever you can’t sleep, spend your time reading.” It’s possible, but the original sentence sounds more like a one-time piece of advice.

музыку is the direct object of the verb послушай (listen [to] what?).

• Nominative: музыка (subject)
• Accusative: музыку (object)

Examples:

• Музыка звучит. – The music is playing.
• Я слушаю музыку. – I am listening to music.

So in послушай музыку, музыку is in the accusative as the thing being listened to.

наушниках is prepositional plural of наушники.

• Nominative plural: наушники (headphones)
• Prepositional plural: в наушниках

With clothing, accessories, and things you wear or have on you, Russian often uses в + prepositional to mean wearing / in / with on:

• в очках – in glasses / wearing glasses
• в шапке – in a hat / wearing a hat
• в куртке – in a jacket
• в наушниках – in headphones / wearing headphones

So послушай музыку в наушниках = listen to music with headphones on / using headphones.
Preposition в here carries that “inside / in / on (as clothing)” meaning.

You’d switch all the 2nd person singular forms (тебе, прочитай, послушай) to their polite plural equivalents:

• Если вам не спится, прочитайте книгу или послушайте музыку в наушниках.

Changes:

• тебе → вам (dative singular → dative plural/polite)
• прочитай → прочитайте (imperative singular → plural/polite)
• послушай → послушайте (imperative singular → plural/polite)

This is appropriate for addressing a stranger, a client, an older person, etc.

It is very natural conversational Russian.

• The structure Если тебе не спится, ... is exactly how people talk about not being able to sleep.
• Using perfective прочитай / послушай is the normal way to give such advice.
• в наушниках is also an everyday phrase.

You could easily say this to a friend or family member; it doesn’t sound bookish or archaic.