Tibi sero ad lectum ire non licet, quia cras mane surgere necesse est.

Because licet normally takes the dative of the person who is allowed or not allowed to do something.

• tibi = to you / for you
• non licet = it is not permitted

So Tibi ... non licet literally means something like:

• To you it is not permitted...

A more natural English translation is simply:

• You are not allowed...

This is a very common Latin pattern:

• mihi licet = I am allowed
• tibi licet = you are allowed
• nobis non licet = we are not allowed

Licet is an impersonal verb meaning it is permitted, it is allowed, or one may.

It is called impersonal because Latin usually uses it in the third-person singular form, without an ordinary personal subject like he, she, or it in the English sense.

So:

• licet = it is permitted
• non licet = it is not permitted

In this sentence:

• Tibi sero ad lectum ire non licet
• literally: To you, to go to bed late is not permitted

Natural English:

• You are not allowed to go to bed late

Because after licet, Latin often uses an infinitive to express the action that is permitted or forbidden.

So:

• ire = to go
• tibi ire licet = you are allowed to go
• tibi ire non licet = you are not allowed to go

In this sentence, the whole infinitive phrase is:

• sero ad lectum ire = to go to bed late

So the structure is:

• tibi = to you
• ... ire = to go...
• non licet = is not permitted

Sero is an adverb, meaning late.

It does not describe a noun; it describes the action ire (to go).

So:

• sero ire = to go late
• more naturally in English: to go late / to go too late / to go to bed late

A learner might expect an adjective, but here Latin uses the adverb sero, just as English uses late adverbially in go to bed late.

This is a normal Latin way to express movement toward bed.

• ad = to / toward
• lectum = bed in the accusative singular
• ire = to go

So literally:

• ad lectum ire = to go to the bed

But idiomatically it means:

• to go to bed

The accusative lectum is used because ad takes the accusative, and because there is motion toward something.

Compare:

• ad scholam ire = to go to school
• ad forum ire = to go to the forum

Because it follows the preposition ad, and ad takes the accusative case.

So:

• lectus = bed, as a dictionary form
• lectum = bed, accusative singular

This is not a direct object of ire. It is accusative because of the preposition:

• ad + accusative

That gives the idea of motion toward a place.

Because non simply negates the verb phrase:

• licet = it is permitted
• non licet = it is not permitted

This is the most straightforward way to say not allowed.

Latin word order is fairly flexible, so the exact position of non can vary more than in English, but non licet is a very standard combination.

So:

• Tibi ... non licet = You are not allowed...

Quia means because. It introduces the reason:

• quia cras mane surgere necesse est
• because it is necessary to get up tomorrow morning

So the sentence has two parts:

1. Tibi sero ad lectum ire non licet

   • You are not allowed to go to bed late

2. quia cras mane surgere necesse est

   • because it is necessary to get up tomorrow morning

This is a simple causal clause with quia.

Yes, and together they make the meaning more precise.

• cras = tomorrow
• mane = in the morning / early in the morning

So:

• cras mane = tomorrow morning

This is perfectly normal Latin. Each word adds something:

• cras tells you which day
• mane tells you what part of the day

Also, mane here is an adverb, not a noun.

This is another impersonal construction.

• necesse est = it is necessary
• surgere = to get up / to rise

So literally:

• surgere necesse est = to get up is necessary

Natural English:

• it is necessary to get up
• or more naturally in context: you have to get up

Just like licet, necesse est often works with an infinitive.

Examples:

• abire necesse est = it is necessary to leave
• laborare necesse est = it is necessary to work

The subject is understood from the context.

The first clause is clearly about you:

• tibi ... non licet = you are not allowed...

So in the second clause, even though Latin does not explicitly repeat you, the sense is:

• because you have to get up tomorrow morning

Latin often leaves this kind of thing implicit when it is obvious.

A more explicit Latin sentence could add a pronoun or use a different construction, but it is not necessary here.

Yes, all of them can express necessity, but they are not exactly the same.

• necesse est = it is necessary
• oportet = it is proper / one ought / it is right that
• debeo = I ought / I must / I owe

In this sentence, necesse est gives a fairly neutral sense of necessity:

• surgere necesse est = it is necessary to get up

It sounds a bit like stating a fact or requirement of the situation, rather than directly commanding someone.

Because both main ideas use impersonal expressions that commonly take an infinitive:

• licet
  • infinitive
• necesse est
  • infinitive

So:

• ire non licet = it is not permitted to go
• surgere necesse est = it is necessary to get up

This is very normal Latin syntax.

Yes. Latin word order is more flexible than English word order.

This sentence is:

• Tibi sero ad lectum ire non licet, quia cras mane surgere necesse est.

But Latin could rearrange parts for emphasis, for example:

• Tibi ad lectum sero ire non licet...
• Quia cras mane surgere necesse est, tibi sero ad lectum ire non licet.

The meaning would stay basically the same, though the emphasis or rhythm might shift.

The given order is natural and clear:

• first the prohibition
• then the reason

Yes, that is a very helpful literal analysis.

Piece by piece:

• Tibi = to you
• sero = late
• ad lectum ire = to go to bed
• non licet = it is not permitted
• quia = because
• cras mane = tomorrow morning
• surgere = to get up
• necesse est = it is necessary

That literal breakdown shows the Latin grammar very well, even though smoother English would be:

• You are not allowed to go to bed late, because you have to get up tomorrow morning.