Because of the numerous variables in the game that are randomly decided (such as weather, crop success, mining, et cetera), it's a good idea to save your game each and every time your character goes to bed. That way, if you wake up in the morning and something is happening that you don't like (or something happens that you don't like throughout the course of the day), you can simply reset your DS and restart the game, hoping for better results. You can repeat this as often as you want.