She doesn't HAVE to be in complete darkness. Like I said, it really depends on each hedgehog's tolerance of light. Some like total darkness, others don't mind a TV/laptop screen, and some (like mine) prefer a moderate amount of light at night. You'll just have to test and see what your baby likes.
Also, if you're worried about her not waking up, most hedgehog owners have to wake their babies up for bonding/cuddling/playtime. Babies sleep a lot, and if left alone, they usually don't wake up until 1 or 2 am. It's important to build a routine to follow daily - that includes turning the lights on/off around the same time every morning and night, cleaning the cage around the same time, and waking your baby up around the same time.
I love my little Tansy [1.3.14] <3
& my boys, Wally [10.6.10], Runner [12.16.2004] and Champ [11.10.2003]