I would never advise anyone leaving their dryer on overnight or when away from home.
Dryers can easily catch on fire and burn you house down while you're asleep or away from home so I would shut the dryer off before going to bed or leaving the house.
A neighbor years ago left his dryer on overnight and it caught on fire and burned the house down but luckily he was able to get out of the house.
Someone happened to be driving home from work at night and noticed his house on fire and was able to get him awake and call the fire department.
So never leave your dryer going overnight even though it may seem safe to do so it's just not worth the risk.