Why is night so hard to resist compulsions. I have this idea in my head or my ocd tells me that my thoughts will be stuck with me or it will become real if I don’t do the compulsion before I fall asleep

For me, my OCD is also worse at night making it difficult to fall asleep without doing the “ritual compulsion” to completion as well. I understand how you feel. Apparently, this is common for people with any and all types of OCD. Night time amplifies these thoughts and feelings for us.

I have a compulsion of thinking I left the stove on so obsessively that I will literally have a nightmare about it and be tormented by the compulsion until I get up out of bed at 3am and go look at it

I have excoriation disorder, and every night around the same time without fail I have an episode. It’s always worse than it is in the day and I don’t know why. My guess is that the quiet of night causes me more anxiety, because my thoughts just run rampant when I’m alone in silence. And like you said, I feel like if I don’t give in to the resulting compulsions than I can’t sleep, because things “just aren’t right” until I do.

This can feel so hard! I often hear people say that mornings or night are particularly rough for OCD acting up. Remember that OCD lies- that's what it does best. It causes you to doubt things and think "well what if". That's why it can be so helpful to work with a ERP specialist to tailor a plan or exercises that best suit you and your OCD symptoms. A therapist can provide support and encouragement along the way. This is such a difficult illness. A ERP trained therapist can help you to sit with the anxiety and discomfort that not doing the compulsions would likely bring and teach you how doing this is important for your brain to recognize that there is no real danger and that what you are really experiencing is a false alarm. As far as the why, well unfortunately I don't have a solid answer as I think it depends on the person experiencing it- I think at night time it makes sense that as we try to unwind and relax from the day we can tend to be more thoughtful which leaves some space for OCD to creep in more heavily.