Questions & Answers about Не выключай свет до утра: мне не спится.
Both are possible, but they feel different because of aspect:
- Не выключай (imperfective) = don’t turn it off / don’t be turning it off (often: keep it on, don’t do that action at all, or don’t do it habitually/in the ongoing situation).
- Не выключи (perfective) = don’t (go and) turn it off (more like a single, one-time “don’t do it” warning). Here, Не выключай свет до утра naturally implies “keep the light on until morning,” so the imperfective imperative fits well.
Very simply: не + imperative form.
- выключай is the imperative (informal singular) of выключать. So Не выключай = Don’t turn off.
выключай is informal singular (talking to one person you address as ты). Other options:
- Informal plural / polite singular: Не выключайте свет до утра.
- A more “one-time” perfective version: Не выключи… (ты) / Не выключите… (вы).