Why can't my sims sleep?

My sims are tired and want to sleep but everytime I send them to bed they always act like they already slept but they are still tired, and it doesn't happen on one save, it also happens on two of my saves! My sims are tired and they want to sleep but they can't do it because they keep skipping the task no matter the energy they have. Please fix this. The game is unplayable with this bug.