What would happen if you would sleep without lying down?

First you notice that your calves are starting to swell a little bit, and your feet look bloated. Then they start becoming discolored, similar to bruising. Then they get open sores and you get really worried because you’ve had to start cutting your pant legs to accommodate the swelling along with new shoes 4 sizes bigger. This and the terrible itching in your calves eventually drives you to the doctor and ur told that being upright all the time has made the valves in your legs’ blood vessels deteriorate to the point where the blood “leaks” back and pools at the bottom of your feet and up in your calves. An even bigger surprise comes when they measure your height and it is over 2 inches shorter then it has always been. This is a very gradual process which doesn’t alarm you until your calves are just open sores and the itching becomes intolerable and you’re using Ace wraps so your pant legs don’t stick to your skin.
It takes about 45 days of laying down even for 4 hours per day to re-gain the height and minimize the swelling. You’ve done some pretty extensive damage to your body and it will make aging more difficult.
There was actually a practice that started during the 17th century, where drunken sailors would pay a couple pence to sleep hung over ropes rather than lying down to sleep.
In the morning the owner of the business would cut/untie the rope, the drunken sleeping sailors would fall tot he ground, wake up and wander back to their ships.
So sleeping without laying down at all is certainly doable, just don’t expect your body to appreciate the mistreatment.