mezamasidokei ga naru mae ni, me ga samemasita.

When a verb comes before 前に, it normally appears in the dictionary/plain non-past form.

• 目覚まし時計が鳴る前に = before the alarm clock rings
• 食べる前に = before eating
• 寝る前に = before sleeping

This is true even if the whole sentence is talking about the past.

So:

• 目覚まし時計が鳴る前に、目が覚めました。 = I woke up before the alarm rang.

Using 鳴った前に would be incorrect here.

前に means before.

It can follow:

• a verb in dictionary form:
  鳴る前に = before it rings
• a noun + の:
  朝ご飯の前に = before breakfast

In this sentence, 目覚まし時計が鳴る前に is a time expression that sets up when the main action happened.

Because 目覚まし時計 is the thing performing the action 鳴る.

• 目覚まし時計が鳴る = the alarm clock rings

The verb 鳴る is intransitive, so the thing that rings is marked with が.

Compare:

• ベルが鳴る = the bell rings
• 電話が鳴る = the phone rings

So が marks the subject of 鳴る.

Because 目が覚める is a fixed expression meaning to wake up or literally one’s eyes awaken/open.

So here:

• 目が覚めました = I woke up

Grammatically, 目 is marked with が, not を.

This expression does not usually mean that your eyeballs did something on their own in a weird literal sense. It is just the normal Japanese way to say woke up.

Both can be translated as woke up, but the nuance is a little different.

• 目が覚めました = I woke up / I came awake
  Focus on becoming conscious.
• 起きました = I got up / I woke up
  Can focus more on getting up from bed or beginning the day.

So in this sentence, 目が覚めました is very natural because the point is that the speaker became awake before the alarm rang.

Because 覚める and 覚ます are different verbs.

• 覚める = to wake up, to come awake
  Intransitive
• 覚ます = to wake something/someone up
  Transitive

Examples:

• 朝、目が覚めた。 = I woke up in the morning.
• 母が私を起こした / 目を覚まさせた。 = My mother woke me up.

In your sentence, the speaker woke up naturally, so 目が覚めました is the right form.

This is another intransitive/transitive pair.

• 鳴る = to ring, to sound
  Something rings by itself
• 鳴らす = to ring, to make something ring
  Someone causes it to ring

Examples:

• ベルが鳴る。 = The bell rings.
• ベルを鳴らす。 = Ring the bell.

In your sentence, the alarm clock is the thing making the sound, so 鳴る is correct:

• 目覚まし時計が鳴る

Because 覚めました is the polite past form of 覚める.

• 覚める = plain non-past
• 覚めた = plain past
• 覚めます = polite non-past
• 覚めました = polite past

The speaker is describing something that already happened, so past tense is needed.

A plain-style version would be:

• 目覚まし時計が鳴る前に、目が覚めた。

Because Japanese tense inside time clauses often works differently from English.

With 前に, Japanese uses the dictionary form to show an action that has not yet happened at that point.

So from the viewpoint of the waking-up moment:

• the alarm had not rung yet
• therefore Japanese says 鳴る前に, not 鳴った前に

This is a very common pattern in Japanese.

Yes. 目覚まし時計 is a compound noun meaning alarm clock.

It is built from:

• 目覚まし = waking up / awakening / something that wakes you up
• 時計 = clock

So together:

• 目覚まし時計 = alarm clock

In everyday Japanese, people also often shorten it to:

• 目覚まし

No, the comma is not grammatically required, but it is very common and helpful.

It separates the time clause from the main clause:

• 目覚まし時計が鳴る前に、目が覚めました。

Without the comma, the sentence is still fine:

• 目覚まし時計が鳴る前に目が覚めました。

The comma just makes it easier to read.

You could, but it has a slightly different feel.

• 目が覚めました = I woke up
• 目を覚ましました = I opened my eyes / I woke myself up / I became awake

In many contexts both may be translated similarly, but 目が覚めました is the more standard expression for simply waking up naturally.

So for your sentence, 目が覚めました sounds very natural.

Yes, but it is usually omitted because Japanese often leaves out obvious subjects.

You could say:

• 私は、目覚まし時計が鳴る前に、目が覚めました。

But in most situations, just saying:

• 目覚まし時計が鳴る前に、目が覚めました。

is more natural, because it is already clear that the speaker is talking about themselves.