Learn Hardcore Polish: W niedzielę leżę długo w łóżku i czytam książkę. - On Sunday I lie in bed for a long time and read a book.

One specific Sunday:
W niedzielę leżę długo w łóżku – This coming Sunday I (plan to) lie in bed for a long time (often with extra context like w tę niedzielę – this Sunday).
Habit / general rule (most typical here):
W niedzielę leżę długo w łóżku… – On Sundays I lie in bed for a long time and read a book.

Polish often uses the singular day name (in accusative) for habits:

W sobotę sprzątam – On Saturdays I clean.
W poniedziałek pracuję z domu – On Mondays I work from home.

You can also use the plural w niedziele (on Sundays) if you really want to stress every Sunday, but the singular is already natural for a habitual action.

Why is there no I (ja) in the sentence?

Polish is a pro‑drop language: the subject pronoun is usually omitted when the verb ending already shows the person.

leżę – 1st person singular (I lie)
czytam – 1st person singular (I read)

Because the endings -ę clearly indicate I, you normally don’t say ja unless:

you want to emphasize contrast:
Ja leżę, a on pracuje. – I lie in bed, and he works.
you want to clarify who is doing the action in a more complex context.

So W niedzielę leżę… already means On Sunday I lie…

If w niedzielę uses the accusative, why is it w łóżku and not w łóżko?

The preposition w can take different cases depending on meaning:

w + locative → where? (location, static)
- w łóżku – in bed (where I am)
- w domu – at home
- w pracy – at work
w + accusative → where to? (movement into) or when? (time)
- wchodzę w pokój – I walk into the room (movement)
- w niedzielę – on Sunday (time)

In your sentence:

w niedzielę – when? → accusative
w łóżku – where? → locative (łóżko → w łóżku)

So the same preposition w can trigger different cases depending on the question it answers.

Why is it w łóżku and not na łóżku?

Both are grammatically correct, but the meaning is slightly different:

w łóżku – literally in bed; normal phrase for being in bed (usually under the covers, resting, sleeping, being lazy).
na łóżku – literally on the bed; more neutral about just being on the surface (sitting, lying, putting things on it).

In everyday Polish, w łóżku is the natural idiom for what you mean here: lying in bed for a long time.

What is the difference between leżę and the dictionary form leżeć?

Leżeć is the infinitive (the form you look up in a dictionary): to lie (in a horizontal position).

Leżę is the 1st person singular present tense:

ja leżę – I lie / I am lying

Basic present tense conjugation of leżeć:

ja leżę – I lie
ty leżysz – you lie (sg., informal)
on/ona/ono leży – he/she/it lies
my leżymy – we lie
wy leżycie – you (pl.) lie
oni/one leżą – they lie

In the sentence, leżę is used because the subject is I.

Does leżę (present tense) mean I am lying in bed now, or that I usually do it on Sundays?

In Polish, the present tense of imperfective verbs (like leżeć, czytać) can express:

Action happening now:
Teraz leżę w łóżku. – I’m lying in bed now.
Regular / habitual action (as in your sentence):
W niedzielę leżę długo w łóżku. – On Sundays I lie in bed for a long time.

Context decides which meaning is intended. Because you have W niedzielę, it naturally reads as a habit, not as right now.

Why is there no comma before i in … w łóżku i czytam książkę?

Polish punctuation rules say:

You do not put a comma before i when it connects two verbs that share the same subject in one clause.

Here:

Subject (understood): ja (I)
Verbs: leżę and czytam
Connector: i (and)

So you write:

leżę długo w łóżku i czytam książkę – no comma.

You would use a comma before i when it connects whole clauses with their own verbs and often their own subjects, for example:

Leżę długo w łóżku, i on też długo leży.
(I lie in bed for a long time, and he also lies for a long time.)

Why is książkę in that form (with -ę) instead of książka?

Książka is the nominative singular form (dictionary form) of a feminine noun: book.

In the sentence, książkę is the direct object of czytam (I read), so it must be in the accusative case:

nominative: książka – a book (subject)
accusative: książkę – a book (object)

Examples:

Książka leży na stole. – The book lies on the table. (subject → nominative)
Czytam książkę. – I’m reading a book. (object → accusative)

So książkę is simply książka changed into the accusative case.

Can I omit książkę and just say W niedzielę leżę długo w łóżku i czytam?

Yes, that is grammatically correct and often natural.

W niedzielę leżę długo w łóżku i czytam.
→ On Sundays I lie in bed for a long time and read.

In Polish, if the object is obvious or not important, you can drop it. Here:

The focus can be on the activity in general: I read (something).
If you add książkę, you make it slightly more specific: I read a book (rather than, say, e‑mails or news).

So both versions are fine, depending on how specific you want to be.

Is there any difference between leżę długo w łóżku and długo leżę w łóżku?

The meaning is the same (I lie in bed for a long time), but there is a slight difference in emphasis / rhythm.

Leżę długo w łóżku – neutral word order, very natural.
Długo leżę w łóżku – puts a bit more emphasis on długo (for a long time), like: I (really) lie in bed for a long time.

Polish word order is relatively flexible, especially with adverbs like długo, but the version in your sentence (leżę długo w łóżku) is the most typical.

How would I say This Sunday I will lie in bed for a long time and read a book (future), not a regular habit?

You have a few natural options. Two very common ones:

Future with “to be” + infinitive (neutral, planned future):
- W tę niedzielę będę długo leżeć w łóżku i czytać książkę.
  (This Sunday I will be lying in bed for a long time and reading a book.)
Future with perfective verbs (focus on completed/limited actions):
- W tę niedzielę długo poleżę w łóżku i poczytam książkę.
  – poleżę / poczytam suggest I will lie / read for a while (and that’s the plan or I’ll have the opportunity to).

Your original sentence with present tense:

W niedzielę leżę długo w łóżku i czytam książkę.

normally reads as a habit, not a one‑time future plan, unless the context clearly makes it about the future.

How do I pronounce the ę at the end of niedzielę and książkę?

The letter ę is a nasal vowel, but at the end of a word it is usually only slightly nasal or even almost like plain “e” in everyday speech.

niedzielę → roughly: nye‑DZYE‑le (with a very light nasal quality on the last vowel; many speakers just say something very close to niedziele).
książkę → roughly: KSHONSH‑ke
- ą is nasal (like on in French bon / Polish wąż)
- ę at the end again is often just a slightly nasal e.

Key point: Don’t over‑nasalize ę at the end of words. A soft e‑like sound is usually acceptable and sounds natural.