I have aphantasia, though I haven't always. I remember as a kid in middle school taking a test and then being able to "see" the page the answer was on. Not sure when it all went dark, but it was sometime during childhood. I only mention all of this because my experience may be atypical.

I have basically no problems with sleep. In fact, I fall asleep extremely quickly and sleep like a rock. I seem to need less sleep than other people and so typically sleep 4-5 hours per night.