The general consensus is that while falling asleep isn’t bad, it is better if you’re able to stay awake. Good to know that I’m not ruining everything by falling asleep! I’ll experiment with leaving light on or different times of day, and the forums also gave me two other ideas to play around with- sitting up instead of laying down, or holding something that i can notice if i drop it.
As was also pointed out, for all I know, I’m not falling asleep at all- just at a different level of consciousness that my brain hasn’t quite adjusted yet. One thing that was repeated in almost all of the threads was that my brain will adjust over time, so just keep pressing forwards.