I don't actually make our bed, neither my wife or I do.

That being said, it isn't a waste of time in and of itself. Making a bed gives you a chance to inspect the sheets, which has multiple benefits. It also means that you'll be making the bottom sheet (whether it be a fitted sheet or a regular sheet folded into place old school) smooth and positioned well.

That pretty much means that the job isn't a waste.

Now, it could be argued that you can gain all of the benefits by just straightening everything up before you go to bed, and that's true usually. The question is if we'll not only do the job right, but be in a state of mind to notice everything well. A lot of people, by the time they're ready to go to bed, don't have the internal resources to ensure that everything is good to go.

You ever hear the term hospital corners? It's a way of making a bed. It ensures that the person using the bed has a smooth surface, free of skin irritating folds. For an ambulatory patient, the benefit of that is minor. But for someone that's in a hospital bed for prolonged times, or that have skin durability issues, or can't communicate discomfort, a well made bed is a necessity.

This translates to situations outside of a clinical setting, just with less consequences should the bedding fail to be smooth. But not zero consequences. Minor as it may be, skin irritation from wrinkled and folded sections of bedding can be severe enough to increase the risk of skin infections. Not a huge risk increase, but it's there.

The process of making the bed also reduces any shed skin, or detritus carried into the bed, which means reduced food sources for anything undesirable. That means an overall reduction in allergens and irritants that can be a problem if you aren't changing sheets daily. It won't remove as much as changing sheets, but you'd be amazed how much is in your sheets after even one night of sleep.

Anything along those lines also carries the possibility of decreasing quality of sleep, which is already a problem millions of people deal with.

Now, we change our sheets often enough to minimize any of those issues, and I run a pass of the vacuum via the furniture/upholstery thingy regularly between changes. Any of the drawbacks to unmade sheets go away under those conditions because they'll get changed again before any buildup can reach problematic levels. Add in the willingness to smooth the sheets out before climbing in, and adjusting the fitted sheet for smoothness works as well.

But, there's a secondary benefit the making the bed that isn't about the bed or sleep.

We humans are strange sometimes. Our minds and brains pull some fuckery on us. For one, habits are easy to break, but hard to build. It's easier to break a small habit than a large one, particularly when tired.

But of more importance is how people in general deal with visual order vs visual disorder. A "mess" tends to shift human behavior in comparison to a neat area. As an example, if you have a perfectly clean table, people coming along are less likely to leave a mess. But if the table already has objects just sitting there, they're more likely to also leave something.

That proclivity occurs in our homes as much as anywhere else. Having a bed made up looks neater than one that is unmade. This can lead to other forms of mess that can cascade into a household wide situation where people, out of nothing but subconscious perception, are more likely to let messes build up.

I can't find the study I'm pulling that from to link to. Not even sure it's available online. So I'm not going to throw out percentages of people leaving more things on an already littered table, but it was high enough when I read it years ago that it stuck in my memory as being very high.

Making a bed perfectly isn't necessary. It doesn't even have to be fully made. But it isn't a waste of time at all, much less a complete waste. And, again, I don't actually make my bed and haven't for decades.

What I do is straighten things up. Untangle sheets and blankets, smooth things out and leave the top bedding in an easy to reach position if I need to crash hard and fast (which is not unusual when my disabilities and medications are a factor).