It is perfectly fine to take a nap! I'm sure you will still be able to sleep at night as if you never took a nap!
If I'm tired in the day, is it alright if I take a nap? I know if you nap you can't sleep at night but some nights I go to bed late.
Yes little nap doesn't hurt anyone but don't nap too long .
From research it found that a little nap about 30 min a day can make you more productive. But be concerned, don't make it more.