Is it bad to fall asleep still in subspace?

My Dom is worried that I sometimes fall asleep during aftercare. He thinks if I don't have time to process and come out of subspace before falling asleep I may be more prone to drop.

I haven't been able to find anything about this. So soft bdsm hive mind, what do you guys think? Do you ever fall asleep during aftercare? Doms, what do you do if your sub falls asleep before they're out of subspace? Is there any harm in it?