Hello and welcome to this forum!
You asked a good question and it was something I asked myself when I had insomnia but felt very sleepy during the day outside my sleeping hours so I wondered if it was okay to take naps since my body obviously wanted it but cbti says naps are strictly forbidden. Also, the way you are asking it is as if it is wrong to take naps and you will get “punished” for it at night. I felt the same at the time too. My answer to myself now and to you is naps are okay, it really doesn’t hurt your nightly sleep as long as it is reasonable. Don’t beat yourself up over it, take the nap when you feel sleepy during the day and nobody is blaming or punishing you for it. Who says not being able to sleep that well at night just because you took an afternoon nap is bad?? It’s your anxious mind that puts that narrative there, you begin to readily believe such nonsense and hereby unnecessarily derived yourself of such a simple pleasure in life.
I now occasionally take naps and still sleep great at night too. I really don’t care what kind of sleep I get at night or how naps might affect my nightly sleep. I think because of that, I continue to sleep great. I have no taboo and I don’t limit myself in any way. Strict rules are not necessary and make no sense. Research already shows power naps improve performance and memory so that’s all I need to know. I seem to do better after naps and I get refreshed and energized. I feel like I could run a marathon after taking a nap so how is that bad? Therefore, please enjoy your siesta. Leave the nightly sleep to the nights. Just listen to your body, if it needs to sleep, it will tell you by making you sleepy.