If your brain is willing and ready to sleep during the day, the light should not make much difference. I fall asleep in my recliner during the day on a regular basis. What is more important is getting your mind to relax and not think in an active way.

Amusement is the term for this kind of thought. You enjoy something but don't have to actively think to enjoy it. I do this with music. The best music is music that you are very familiar with. That way, you just listen rather than try to comprehend the lyrics.

Think of how women like to cuddle. They enjoy the closeness but don't need to talk to enjoy it. They feel a sense of acceptance and security so their mind or emotions can let go and just relax.