Joh In this case, a box with a time lock is a safe way to store the key and then remove it in the morning.
If you want to give it a try, opt for a box that you can open with force if necessary. For the worst case situation.
Thanks for the tip, I'll keep it in mind. In a pinch, my Mother has a key (she also has a belt, though it is a sex toy and used for that purpose). I recall when my Dad was trying to quit smoking he'd leave the cigarettes in the car or the garage or something. It made it inconvenient to get a cigarette (one often lights up without thinking) and it made it obvious to everybody he was going out after one. With winter coming on soon having to go out in the cold to get the key (especially since I sleep naked or almost) would be a good discouragement.