Αν πιω καπουτσίνο μετά τις έξι, η καφεΐνη με κρατάει ξύπνιο και δεν κοιμάμαι καλά.

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Breakdown of Αν πιω καπουτσίνο μετά τις έξι, η καφεΐνη με κρατάει ξύπνιο και δεν κοιμάμαι καλά.

• πίνω: to drink
• και: and
• δεν: not

Questions & Answers about Αν πιω καπουτσίνο μετά τις έξι, η καφεΐνη με κρατάει ξύπνιο και δεν κοιμάμαι καλά.

Why is πιω used after αν instead of πίνω?

After αν in this kind of sentence, Greek normally uses the subjunctive.
πιω is the aorist subjunctive of πίνω.

Here, αν πιω means if I drink on a particular occasion. It does not mean past time.

• αν πιω καπουτσίνο = if I drink a cappuccino
• αν πίνω καπουτσίνο = if I am drinking cappuccino / if I drink cappuccino habitually

So πιω fits better because the sentence is talking about a single possible event that leads to a result.

If πιω is an aorist form, why doesn’t it mean I drank?

Because in Modern Greek, the aorist stem does not automatically mean past. What matters is the whole construction.

• ήπια = I drank → past
• να πιω = to drink / that I drink
• αν πιω = if I drink

So πιω here is not a past tense. It is an aorist subjunctive, and the aorist idea is about the action as a whole event, not about past time.

Why is there no article before καπουτσίνο? Could I say έναν καπουτσίνο?

Yes, you could say , but the version without it is also natural.