Which tense should be used in these sentences?
It should not be Present continuous because it is a general habit. However, the other tense is simple weird to me.
what do you think/are you thinking about at night before you fall asleep?
I think/am thinking about all of the pleasant things that happened during the day.
I do not think/am not thinking about my problems.
Thank you in advance.
I'm not sure why you think the present simple is weird. It is the tense we use for habitual actions.
What do you think about at night before you fall asleep?
I think about all the nice things that happened during the day.
I don't think about my problems.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.