Losing is part of gambling, and the duration of how long you can forget your losses depends on the amount and the circumstances, if you’ve just gone on a string of winnings. When you think of cashing out, you put all your winnings in one bet, considering it’s your lucky night and nothing could go wrong, only to lose everything. Now that will make you lose sleep, and it will take days or even weeks to recover.

This happened to me, and it took me almost two weeks to recover, but if it's a loss that you can expect to happen, I can easily forget it in one or two days.
Gambling should be fun, and losses are part of it, so you will have to get over it quickly so you can continue playing.