Learn Hardcore Russian: Психолог объяснил ей, что лёгкая тревога естественна даже тогда, когда не спится. - The psychologist explained to her that slight anxiety is natural even when you can’t sleep.

Психолог — subject (nominative)
объяснил — verb (past, masculine)
ей — “to her” in dative (кому?)
что лёгкая тревога естественна… — the thing being explained (a whole subordinate clause)

Ей is dative of она (she).
Её is accusative/genitive of она and would mean “explained her”, which is ungrammatical here.

Word order can change without changing the case:

Психолог объяснил ей…
Психолог ей объяснил…
Ей объяснил психолог…

All of these keep ей in the dative, because she is the person being explained to.

What is the difference between естественна and естественная? Why is the short form used here?

Russian has two types of adjective forms:

Full form: естественная
Short form: естественна

In the sentence we have:
лёгкая тревога естественна — “mild anxiety is natural.”

Short-form adjectives (like естественна):

are used predicatively (in the “X is Y” position)
agree in gender and number but not in case
- feminine singular: естественна
- masculine: естественен
- neuter: естественно
- plural: естественны
often describe a temporary or situational state, or sound more neutral/statement-like

Full-form adjectives (like естественная):

can be both attributive (“a natural reaction”) and predicative
when used predicatively, they can sound:
- more descriptive of a permanent quality
- sometimes a bit heavier or bookish in this kind of sentence

Compare:

Лёгкая тревога естественна.
→ A neutral statement: “Mild anxiety is (quite) natural.”
Лёгкая тревога естественная.
→ Grammatically possible, but feels more like you’re qualifying what kind of anxiety it is (as if contrasting with an unnatural anxiety), or sounds stylistically heavier.

In this context, естественна is the most natural-sounding choice in Russian.

How do gender and agreement work in лёгкая тревога естественна? Why not лёгкий тревога естественный?

Let’s break it down:

тревога — “anxiety”
- ends in -а → typically feminine noun
- nominative singular: тревога
лёгкая — “light, mild”
- feminine, nominative, singular form of лёгкий
- it has to agree with тревога in gender, number, and case

So:

лёгкая тревога = “mild anxiety”
(feminine adjective + feminine noun)

If you said:

лёгкий тревога естественный — this is wrong, because:
- лёгкий is masculine, but тревога is feminine
- естественный is masculine, but the subject is feminine

The predicate adjective also agrees in gender/number with the subject:

subject: лёгкая тревога → feminine, singular
predicate (short form): естественна → feminine, singular

So you get:

Лёгкая тревога естественна.
“Mild anxiety is natural.”

What does не спится mean literally, and what kind of verb form is it?

Не спится comes from the verb спаться, which is the reflexive form of спать (“to sleep”).

Grammatically:

It is an impersonal reflexive form:
- спится — literally “is slept” / “sleeps itself”
- used without a subject in the nominative
не спится means something like:
- “it doesn’t sleep”
- idiomatically: “one can’t sleep” / “I can’t sleep” / “you can’t sleep”, depending on context

Often, you can add a dative pronoun to show who can’t sleep:

Мне не спится. — I can’t sleep.
Ей не спится. — She can’t sleep.
Им не спится. — They can’t sleep.

In your sentence, we have a more general, subjectless phrase:

когда не спится — “when (you / one / people) can’t sleep”

It describes a general state where sleep doesn’t come, not a deliberate action of “not sleeping”. That’s different from:

я не сплю — “I am not sleeping” (a conscious action/state)
мне не спится — “I can’t sleep” (sleep won’t come)

Why is there no explicit subject in когда не спится? Who is not sleeping?

Russian allows impersonal constructions, where:

there is no grammatical subject in the nominative
the verb is typically 3rd person singular (as in спится)
the sentence describes a state of affairs rather than an action of a specific person

Когда не спится literally means “when it doesn’t sleep (itself)”, but idiomatically:

it talks about an unnamed person / people in general
it matches English “when you can’t sleep” / “when one can’t sleep”

If we want to specify who, we use a dative:

Когда мне не спится… — when I can’t sleep…
Когда ей не спится… — when she can’t sleep…

In your sentence, the idea is general:

…even at times when (one) can’t sleep.

So the person is understood from context, not grammatically expressed.

Is когда не спится present, past, or future?

Formally, спится is present tense (3rd person singular).

However, in this type of sentence:

когда не спится has a generic meaning:
- “whenever (one) can’t sleep”
- “in situations when you can’t sleep”

So it does not refer to one specific moment in time. It’s about a repeated or typical situation, an “any time this happens” meaning.

If you were talking about a specific time in the past, you might say:

…даже тогда, когда мне не спалось. — “…even then, when I couldn’t sleep.”
(past form спалось)

For the general statement in your sentence, когда не спится (present generic) is the natural choice.

What does даже тогда, когда add here? Could we just say даже когда не спится?

Both are possible, but they differ slightly in nuance.

даже когда не спится
→ “even when you can’t sleep”
→ a bit shorter, more conversational
даже тогда, когда не спится
→ literally “even at those times when you can’t sleep”
→ тогда (“then/at that time”) adds a bit of emphasis on the time period
→ slightly more emphatic or careful, stylistically a bit more “written”

So:

meaning is basically the same
тогда strengthens the feeling of “even in those very moments…”

You could simplify it to:

…естественна даже когда не спится.

and the sentence would still be correct and natural.

Why are there commas before что and когда in this sentence?

In Russian, commas are used before many subordinating conjunctions that introduce clauses.

Your sentence:

Психолог объяснил ей, что лёгкая тревога естественна даже тогда, когда не спится.

Comma before что
- что introduces an object clause — what he explained
- The structure is:
  - Психолог объяснил ей — main clause
  - что лёгкая тревога естественна… — subordinate clause (object of “объяснил”)
Rule: place a comma before что when it introduces a subordinate clause.
Comma before когда
- когда не спится is a time clause modifying “естественна”
- даже тогда, когда не спится = “even at times when (one) can’t sleep”
Rule: place a comma before когда when it introduces a subordinate adverbial clause of time.

So both commas mark the beginning of subordinate clauses, similar to many commas before “that / when” in more complex English sentences.

Can we change the word order Психолог объяснил ей? For example, Психолог ей объяснил or Ей объяснил психолог?

Yes, Russian word order is flexible. All of these are grammatically correct:

Психолог объяснил ей, что…
- neutral order: Subject – Verb – Indirect object
- quite standard
Психолог ей объяснил, что…
- slight shift of focus to ей (“to her”)
- can suggest contrast (e.g. “He explained to her (not to others)”)
Ей объяснил психолог, что…
- fronting ей strongly emphasizes “to her”
- also puts психолог in a more “new information / contrast” position, as if:
  - “It was the psychologist who explained to her that…”

In all versions:

ей stays in dative, indicating “to her”
the meaning core is the same; only focus and emphasis change

How would the sentence change if the psychologist were female, or if the pronoun “her” changed to “him” or “me”?

Two things can change:

Gender of the psychologist (past tense verb)
- Current: Психолог объяснил ей…
  - объяснил — masculine past tense
- If the psychologist is female:
  - Психолог объяснила ей, что…
    (объяснила — feminine past)
The noun психолог itself doesn’t change; only the verb shows gender in the past.
Person you explain to (dative pronoun)
The pattern is still: объяснить кому? (dative)
- to her: объяснил ей
- to him: объяснил ему
- to me: объяснил мне
- to us: объяснил нам
- to them: объяснил им
Example variations:
- Психолог объяснил ему, что лёгкая тревога естественна…
  — “The psychologist explained to him that mild anxiety is natural…”
- Психолог объяснила мне, что лёгкая тревога естественна…
  — “The (female) psychologist explained to me that mild anxiety is natural…”

How are the tricky words in this sentence stressed and pronounced?

Here are the key words with stress and a rough phonetic hint (in Latin letters):

психолог — психОлог → psikhÓ-log
объяснил — объяснИл → ab-yas-nÍl
лёгкая — лЁгкая → LYÓHK-ka-ya
тревога — тревОга → trevÓ-ga
естественна — естЕственна → yestÉ-stven-na
тревога естественна: трЕвога естЕственна
спится — спИтся → SPÍ-tsa
whole phrase: когда не спится — когдА не спИтся → kagDÁ nye SPÍ-tsa

Remember:

ё is always stressed and sounds like “yo”: лёгкая → lyÓhkaya
each word here has one main stress, and getting that right helps your pronunciation sound much more natural.