Why do seniors sleep all day?

If they sleep a lot, all day, all night, I would suspect depression. My mother stays in bed a lot when she is depressed, especially in the winter and she is 95 years old.

This is not a funny topic, but my healthy 68 yo hubby hasn't gotten out of bed today yet and it is almost 5:00 pm. He might get up for dinner, might not. But he'll sleep all night tonight too. Went to bed last night at 6 pm.

He's ALWAYS had this weird sleep cycle. It is getting worse the older he gets.

Mostly, I think, he's bored.

My dad sleeps a lot for a combination of reasons, boredom, getting up a lot at night to use the bathroom, not sleeping well at night in general—likely due to arthritis and end stage congestive heart failure, low oxygen levels, nothing else to do, and being a person who’s always enjoyed a nap. I see no harm, his days are hard

My grandmother used to complain of "insomnia" and (supposedly) being up all night without a reason for it. In reality, she napped frequently through the daytime hours such that her nighttime sleep probably was disturbed to some extent.

Somewhat more recently, I hired an aide for a lady so that the lady would be kept occupied/stimulated through the day and would not constantly nod off. My thinking was that she would then be tired and sleep at a more normal time and sleep through the night. Not sure that it ever worked - lady would still wake up at 2 AM ready for the day (believing it was morning and thinking she had slept) and then sleep in front of the TV at odd times during the day.

I'm told sleep patterns change quite a bit in the aging process, but I don't know the science behind it. The lack of sleeping definitely becomes apparent when caregivers are on scene and someone takes note of the sleep patterns - elder doesn't always know they slept or for how long.

A bit more information would help. Is he awake all night? Or just sleeping lots? If he is still sleeping at night, and napping during the day likely he is tired.