Another reason to feel guilty for not working out
We have long known that the young (both people and mice) tend to be more active than the elderly. And furthermore, that the older one gets (whether one is a mouse or a person), the more random one's activity patterns tend to be. Your overall activity level goes down, and you are more likely to be active at random, inconvenient times. Older people may find themselves restless in the middle of the night, and tired in the middle of the day.