Learn Hardcore Russian: Иногда чувство усталости мешает мне учить грамматику. - Sometimes the feeling of tiredness prevents me from studying grammar.

In the phrase чувство усталости, why do we use both чувство and усталости? Could we just say Иногда усталость мешает мне учить грамматику?

Both versions are correct, but they are slightly different in nuance.

Иногда усталость мешает мне учить грамматику.
Here усталость is used on its own: tiredness, fatigue as a state.
Иногда чувство усталости мешает мне учить грамматику.
Literally: Sometimes the feeling of tiredness prevents me from studying grammar.

Using чувство усталости:

makes it sound a bit more descriptive or psychological: the sensation / the feeling of being tired;
can imply that you become aware of this feeling and it starts getting in the way.

Using just усталость is a bit more direct and neutral. In many everyday contexts, усталость alone is more common. The version with чувство just adds a small stylistic nuance, not a big grammatical difference.

Why is it усталости and not усталость after чувство?

Because чувство (feeling) normally takes a noun in the genitive case.

The pattern is:

чувство чего? (feeling of what?) → genitive

Examples:

чувство радости – a feeling of joy
чувство страха – a feeling of fear
чувство холода – a feeling of cold
чувство усталости – a feeling of tiredness

So усталость (nominative) changes to усталости (genitive) to fit чувство чего?

Why is it мешает мне, with мне in the dative, not мешает меня?

The verb мешать has two main patterns, with two different meanings:

мешать кому? (dative) – to disturb / hinder / prevent someone
- мешать мне – to disturb / hinder me
- мешать ему – to disturb / hinder him
мешать что? (accusative) – to mix / stir something
- мешать суп – to stir the soup
- мешать салат – to mix the salad

In your sentence:

Иногда чувство усталости мешает мне учить грамматику.
Here it clearly has meaning (1): tiredness is preventing me from studying grammar, so it must be кому? → мне (dative).

Мешает меня would be ungrammatical in this meaning. With мешать meaning to prevent / be in the way, you always use the dative for the person affected.

What is the literal meaning of мешать here? Does it mean to mix, to disturb, or to prevent?

The verb мешать is polysemous; it has several meanings:

мешать что? – to mix / stir
- мешать тесто – to mix the dough
- мешать сахар в чае – to stir sugar in (one’s) tea
мешать кому? – to disturb / hinder / be in the way / prevent
- Ты мне мешаешь работать. – You are disturbing / preventing me from working.
- Шум мешает детям спать. – The noise prevents the children from sleeping.

In Иногда чувство усталости мешает мне учить грамматику, it is sense (2):
мешать кому? делать что? → to prevent someone from doing something.

A very natural translation is:

Sometimes the feeling of tiredness keeps me from studying grammar.
Sometimes the feeling of tiredness prevents me from studying grammar.

Why do we use мне and not я or меня? What case is мне?

Мне is the dative case of я.

Russian cases for я:

nominative: я – I
genitive: меня – of me
dative: мне – to/for me
accusative: меня – me
instrumental: мной – by/with me
prepositional: обо мне – about me

The verb мешать in the sense to hinder / disturb requires кому? (dative) for the person who is affected:

мешать кому?
- мне – to me
- тебе – to you
- ему / ей – to him / her
- нам – to us
- им – to them

So:

чувство усталости мешает мне – the feeling of tiredness is getting in my way.

Using я (nominative) or меня (accusative) here would break the required pattern of мешать кому?

Why is it учить грамматику and not учиться грамматике?

Учит�� and учиться are related but used differently:

учить что? (accusative) – to learn / to study something or to teach something
- учить грамматику – to learn grammar
- учить слова – to learn (memorize) words
учиться чему? (dative) – to learn / study something in general, to be learning
- учиться грамматике – to be learning/studying grammar
- учиться русскому языку – to be learning Russian

In practice:

учить грамматику often feels a bit more direct: working on rules, exercises, drilling patterns;
учиться грамматике sounds a bit more general and process-oriented.

Both are grammatically correct here. The sentence with учить suggests actively studying / learning grammar material (e.g. rules, exercises). Using учиться грамматике would slightly shift the focus to the general process of learning grammar.

Why is грамматику in the accusative case?

Because учить in this meaning follows the pattern:

учить кого? что? (accusative)

Examples:

учить грамматику – to learn grammar
учить слова – to learn words
учить стихотворение – to learn (memorize) a poem

So грамматика (nominative) becomes грамматику (accusative) as the direct object of учить.

If you were saying to teach someone grammar, the pattern changes:

учить кого‑то чему?
- учить детей грамматике – to teach children grammar

Here детей is accusative (who is being taught), and грамматике is dative (what they are being taught). But in your sentence, you are learning grammar yourself, so it’s simply учить грамматику (accusative).

Why do we use the infinitive учить, not выучить or some other perfective form?

Учить is imperfective, and that matches the meaning of a repeated, ongoing action:

Иногда чувство усталости мешает мне учить грамматику.
→ Sometimes, on various occasions, tiredness interferes with my studying grammar (as an activity).

If you used a perfective like выучить:

мешает мне выучить грамматику
This sounds more like prevents me from (ever) learning/mastering grammar completely, as one overall result.

So:

учить грамматику – to be engaged in studying grammar, in general, over time;
выучить грамматику – to finish learning grammar, to learn it to completion.

The sentence with иногда and a regular difficulty fits better with the ongoing, repeated sense of учить (imperfective).

Can we change the word order? For example, is Чувство усталости иногда мешает мне учить грамматику also correct?

Yes, the word order is flexible, and your variant is correct:

Иногда чувство усталости мешает мне учить грамматику.
Чувство усталости иногда мешает мне учить грамматику.

Both are grammatical; the difference is one of emphasis and rhythm:

Starting with Иногда emphasizes how often / when this happens:
Sometimes, the feeling of tiredness gets in the way…
Starting with Чувство усталости puts more focus on what is the problem:
The feeling of tiredness sometimes gets in the way…

In everyday speech, both word orders sound natural.

Is it possible to just say Иногда усталость мешает мне учить грамматику? How is that different from чувство усталости?

Yes, Иногда усталость мешает мне учить грамматику is completely correct and very natural.

Difference in nuance:

усталость – tiredness as a state, condition:
Sometimes tiredness keeps me from studying grammar.
чувство усталости – the feeling of tiredness, the sense of being tired:
Sometimes the feeling of tiredness keeps me from studying grammar.

In many contexts, using just усталость is simpler and more common. Чувство усталости can sound a bit more descriptive, introspective, or literary, but it is not strange or wrong in normal speech either.

How would you say something similar in another natural way in Russian?

Several natural alternatives:

Иногда усталость не даёт мне учить грамматику.
– Sometimes tiredness doesn’t let me study grammar.
Иногда я слишком устал, чтобы учить грамматику.
– Sometimes I’m too tired to study grammar.
Иногда из‑за усталости я не могу учить грамматику.
– Sometimes because of tiredness I can’t study grammar.

All keep the same basic idea, with small stylistic differences.