I've got some more questions for you, if you don't mind.
Have you checked to make sure the “Reverse Day/Night" option is checked “No”? If it is checked "Yes", the family members will be tired during the day, and wake and refreshed at night.
What does your little family have to sleep on? A family of 2 doesn’t seem to mind sleeping the first night on the sofa, but a bed would work better for more sleep!
Are there enough beds in the home so that everyone has a place to sleep?
You can try placing the family members in bed with the game open and watch their sleep cycle. Normally they will sleep for a few minutes and get up. When they do get up their ‘status’ may say ‘tired’ rather than exhausted (depending on how exhausted they are). You can do this a couple of times to see if their status improves.
Of course, if there are little children running around the house being disruptive, it interferes with the sleep cycle and the cycle will need to be started over.