Перед сном я снова посмотрел на градусник и понял, что мне стало лучше.

Перед means before / in front of, and when it refers to time, it still takes the instrumental case.

So:

• сон = sleep
• сном = instrumental singular of сон

So перед сном literally means before sleep, but in natural English it is often before going to sleep or before bed.

This is a very common pattern:

• перед уроком = before class
• перед работой = before work
• перед ужином = before dinner

This is about aspect.

• смотреть = imperfective, looking / watching / used to look
• посмотреть = perfective, to take a look / to look once and complete the action

In this sentence, the speaker means he took a quick look at the thermometer once, so посмотрел is the natural choice.

Compare:

• Я смотрел на градусник. = I was looking at the thermometer / I looked at it for some time.
• Я посмотрел на градусник. = I looked at the thermometer (once, completed action).

Because this is part of a sequence of completed past actions:

1. he looked at the thermometer
2. he realized he felt better

the perfective form fits very well.

The verb смотреть / посмотреть normally goes with на + accusative when you mean to look at something.

So:

• смотреть на кого? что?
• посмотреть на кого? что?

That gives:

• на градусник

Examples:

• смотреть на небо = to look at the sky
• посмотреть на часы = to look at the clock/watch
• смотреть на ребёнка = to look at the child

Without на, the sentence would sound wrong with this verb.

Градусник is the common everyday word for thermometer, especially a body thermometer used when someone is sick.

Термометр is also correct, but it is a bit more formal or technical.

So in this sentence:

• градусник = thermometer

A learner should know that Russians very often say градусник in ordinary conversation.

In Russian, past tense verbs agree with the subject in gender and number.

Here the subject is я, but Russian past tense still shows gender:

• я посмотрел, понял = a male speaker
• я посмотрела, поняла = a female speaker

So this sentence is spoken by a man or by a narrator referring to a male speaker.

This is something English speakers often notice because English past-tense verbs do not show gender.

Because что introduces a subordinate clause.

Main clause:

• я снова посмотрел на градусник и понял = I looked at the thermometer again and realized

Subordinate clause:

• что мне стало лучше = that I felt better / that I had gotten better

Russian normally puts a comma before что in this structure:

• Я знаю, что...
• Я думаю, что...
• Я понял, что...

So the comma is required.

This is one of the most important points in the sentence.

Мне стало лучше is the normal Russian way to say:

• I felt better
• I got better
• I became better

Literally, it is something like:

• to me it became better

This uses:

• мне = dative, to me
• стало = it became
• лучше = better

By contrast, я стал лучше usually means something more like:

• I became a better person
• I improved
• I became better than before in a broader sense

It does not sound like the normal way to say your health improved.

For physical condition, Russian strongly prefers:

• мне лучше = I feel better
• мне стало лучше = I started feeling better / I got better

Because this is an impersonal construction.

There is no normal grammatical subject like я controlling the verb. Instead, Russian uses a neutral impersonal form:

• мне стало лучше

The verb appears in the neuter singular past form:

• стало

This is very common with expressions of physical or emotional state:

• мне стало плохо = I started feeling bad
• ему стало холодно = he became cold
• ей стало страшно = she became frightened

So стало does not agree with мне. The dative pronoun is not the grammatical subject.

Лучше is the comparative form of хорошо and often means better.

In this sentence, it refers to the speaker’s condition, so:

• мне стало лучше = I felt better / my condition improved

It does not necessarily mean completely well. It just means better than before.

Related expressions:

• мне лучше = I feel better
• ему намного лучше = he feels much better
• ей уже лучше = she already feels better

Yes, опять could also be used here.

Both снова and опять can mean again. In many contexts they are interchangeable.

• снова often sounds a little more neutral or literary
• опять can sometimes sound more conversational, and sometimes it can carry an emotional tone like again!

Here:

• я снова посмотрел на градусник
• я опять посмотрел на градусник

Both are possible.

The original sentence with снова sounds perfectly natural and slightly neutral in tone.

Russian word order is flexible, but the neutral order here is very natural:

• Перед сном я снова посмотрел на градусник...

This puts the time expression first:

• Перед сном = before going to sleep

Then the subject:

• я

Then the adverb:

• снова

Then the verb:

• посмотрел

You could change the order, but the emphasis would change a little. For example:

• Я перед сном снова посмотрел на градусник.
• Снова я посмотрел на градусник перед сном.

The original version sounds the most natural and unmarked in ordinary narration.

Literally it is before sleep, but in normal usage it usually means:

• before going to sleep
• before bed
• at bedtime

So this is an idiomatic, natural Russian time expression.

English usually needs a slightly freer translation here rather than a word-for-word one.

Yes. Depending on context, several English translations work:

• that I felt better
• that I was feeling better
• that I had gotten better
• that I was getting better

The Russian phrase itself simply says that the speaker realized his condition had improved.

The exact English wording depends on how smooth or natural you want the translation to sound in context.

Because Russian often expresses physical or emotional states with an impersonal pattern instead of using a direct equivalent of feel.

English:

• I felt better

Russian:

• мне стало лучше

This is a very typical difference between the two languages. Russian often prefers:

• мне холодно = I am cold
• мне грустно = I am sad
• мне стало плохо = I started feeling sick / I felt bad
• мне стало лучше = I felt better

So even though English uses I felt, Russian does not need a verb meaning feel here.

In this sentence, realized is usually the best English translation.

• понял literally means understood
• but in context, after looking at the thermometer, the natural meaning is realized

So:

• я понял, что мне стало лучше = I realized that I felt better

This is a common translation choice: the Russian verb stays the same, but English chooses the most natural verb for the situation.