MJ sleeps about 12-13 hours... she falls asleep anywhere around 6pm - 8 pm the latest. I leave home for work at 4:30 am.. and i turn her lights on as I dont get home until about 4 pm. Even with the lights on.. when she doesnt feel like waking up she stays asleep until later. On the weekends when we sleep together, she falls asleep before me and wake up wayy after me.. which is about 12 hrs. So no worries.. even if lights on is at 6.. they'll still be able to sleep =)