Learn Hardcore Russian: Когда я чувствую сильную сонливость днём, я стараюсь немного поспать. - When I feel strong sleepiness during the day, I try to sleep a little.

сонливость = a persistent feeling of wanting to sleep / drowsiness
усталость = tiredness, fatigue (you can be усталый even without wanting to fall asleep)
(я) хочу спать = “I want to sleep / I’m sleepy” (a direct statement, more colloquial)

So сильную сонливость is “strong drowsiness / very sleepy feeling,” focusing specifically on the urge to sleep, not just low energy or general fatigue.

Why is it сильную сонливость and not some other ending? What’s going on with the grammar here?

Сонливость is a feminine noun (like мать, ночь, жизнь) ending in -ость.

Base (nominative) form: сонливость (feminine)
In the sentence it is the direct object of чувствую (“I feel”), so it must be in the accusative case.
Feminine nouns in -ость have the same form in nominative and accusative: сонливость.
The adjective сильный must agree with it in gender, number, and case:
- feminine, singular, accusative → сильная → сильную

So we get сильную сонливость = “strong sleepiness” (object of “I feel”).

What case is днём, and why does it mean “in the daytime / during the day”?

Днём is the instrumental singular form of день.

However, in expressions of time, some instrumental forms are used adverbially to mean “at/in (that time of day)”:

утром (< утро) = in the morning
днём (< день) = in the daytime / during the day
вечером (< вечер) = in the evening
ночью (< ночь) = at night

So днём here literally is “by day,” but functionally it’s just “during the day / in the daytime.” It’s a very standard way to talk about time-of-day in Russian.

Why is there a comma before я стараюсь?

The sentence has two clauses:

Когда я чувствую сильную сонливость днём – subordinate (dependent) clause, introduced by когда (“when”).
я стараюсь немного поспать – main clause.

In Russian, when a subordinate clause (with когда, если, потому что, что, чтобы, etc.) comes before the main clause, you normally put a comma between them. So:

Когда … , (то) … → comma is required.

If you reversed the order, you’d still have a comma:

Я стараюсь немного поспать, когда я чувствую сильную сонливость днём.

What does стараюсь mean exactly, and why does it have the reflexive ending -сь?

Стараться is a reflexive verb meaning “to try / to make an effort.”

infinitive: стараться
1st person singular: я стараюсь (I try / I make an effort)

The -сь here is historically a reflexive ending, but in modern Russian for verbs like стараться it mostly marks a “middle voice” meaning (internal effort), not literal “doing something to yourself.”

Rough English equivalents:

я стараюсь немного поспать = I try to sleep a bit / I make an effort to sleep a bit.

It’s more about general effort or intention, not a single attempt at a specific moment (for that пытаться is more straightforward).

What’s the difference between стараюсь and пытаюсь here? Could I say я пытаюсь немного поспать?

You can say я пытаюсь немного поспать, but there’s a nuance:

стараюсь – I make an effort / I do what I can (more about overall effort, often habitual or “I try to live this way”).
пытаюсь – I attempt something, often more concrete, like a specific attempt that may fail.

In this general, habitual sentence about what you do when you feel sleepy, стараюсь sounds very natural and fits well: it’s like “I generally try (as a habit) to get a little sleep.”
Пытаюсь would sound a bit more like “I attempt, but it’s often difficult / doesn’t always work.”

Why is чувствую in the present tense after когда? Could it be future or past?

In Russian, for general truths and habits, you often use the present tense, even when English might use other structures.

Here, Когда я чувствую сильную сонливость днём, я стараюсь… describes a repeated situation (whenever this happens, I do that), so the present tense is natural in both clauses.

You can change tenses if you’re talking about a specific time frame:

Past habit: Когда я чувствовал сильную сонливость днём, я старался немного поспать. – “When I felt very sleepy during the day, I (would) try to sleep a bit.”
Future specific: Когда я почувствую сильную сонливость днём, я постараюсь немного поспать. – “When I (will) feel very sleepy during the day, I will try to sleep a bit.”

But for general habits, plain present is the default.

Why is it стараюсь немного поспать without any word like “to” or чтобы in between?

In Russian, many verbs (including стараться) are directly followed by an infinitive:

стараюсь понять – I try to understand
стараюсь помочь – I try to help
стараюсь немного поспать – I try to sleep a bit

No extra word like “to” or чтобы is needed; the infinitive itself shows the purpose or target of the effort.

Чтобы + infinitive has a slightly different feel (purpose clause):

Я стараюсь, чтобы немного поспать sounds awkward or overly complicated here and is usually not used in this simple structure.

Why поспать and not just спать? What’s the difference between them?

Спать and поспать have different aspects:

спать – imperfective; “to sleep” as an ongoing state or general ability.
поспать – perfective; “to sleep for a while / for some time” (completed action with some duration).

In немного поспать, the perfective поспать is natural because:

немного = “a little / for a short time,”
perfective + duration = “to sleep for that limited period and be done.”

So немного поспать ≈ “to have a bit of a sleep / to sleep for a short while,” which fits the idea of taking a short nap.

Could I just say Когда я чувствую сильную сонливость днём, я немного сплю? Does it mean the same thing?

You can say it, and it is grammatically correct, but the nuance changes:

я стараюсь немного поспать – “I try to sleep a bit” (focus on intention/attempt; maybe it doesn’t always work).
я немного сплю – “I sleep a bit” (sounds more like a fact: I actually do sleep for a while).

The original sentence emphasizes the effort or strategy in response to daytime sleepiness.
Your version sounds more like a straightforward description of what in fact happens.

Can the word днём be placed somewhere else in the sentence? For example, Когда я днём чувствую… or Когда я чувствую днём…?

Yes, Russian word order is flexible, and these are all acceptable:

Когда я чувствую сильную сонливость днём, я стараюсь немного поспать.
Когда я днём чувствую сильную сонливость, я стараюсь немного поспать.
Когда днём я чувствую сильную сонливость, я стараюсь немного поспать.

They all mean essentially the same thing. The most neutral is probably the original, with днём near the phrase it semantically modifies (чувствую сильную сонливость). Moving днём earlier can give it a bit more emphasis (“When during the day I feel…”).

Can I drop the second я and say: Когда я чувствую сильную сонливость днём, стараюсь немного поспать?

Yes, that is perfectly natural Russian.

Russian doesn’t require repeating the subject pronoun when it’s clear from context and verb endings:

Когда я чувствую сильную сонливость днём, стараюсь немного поспать.

The verb стараюсь clearly shows 1st person singular, so leaving out the second я is fine and often sounds more fluid in speech and writing.

How do you pronounce the tricky words here, especially сонливость, днём, and стараюсь?

Approximate stress and pronunciation:

сонлИвость – stress on -ли-
- [san-LI-vosʲtʲ]
днём – stress on ё
- [dnʲom] (single syllable, the дн cluster is pronounced together)
стараЮсь – stress on -юсь
- [sta-RA-yusʲ] (the -юсь has a clear [yusʲ] sound)

Remember that ё is always stressed, so днём automatically has the stress on that syllable.