Forty-three percent of Americans say they’re too tired to function. So, odds are, you’re pretty exhausted. Some mornings, you might even fantasize about staying in bed…forever. Hey, look, your wish came true! You’ve got food, a bedpan, and an endless stream of podcasts to binge. Everything you need to never move again. But it won’t be long until you realize that you’ve made a terrible mistake. People spend lazy Sundays or sick days in bed all the time and are no worse for wear, but if you don’t start moving again after about 24 hours, one of the first things to change is your lungs. Gravity isn’t pulling them down into their normal position anymore, so the lower part of your lungs will crumple up. You probably won’t feel any different, but watch out, because it’s harder for mucus to pass through those collapsed passages. So it can get trapped, which can infect your lungs and ultimately lead to pneumonia. That’s why doctors tell people on bed rest to sit up and cough from time to time. But you’re way too engrossed in those podcasts to remember to cough. Within a week, your problems only get worse. You see, normally, your muscles and bones help support your weight under gravity. But now that you’re lying down, they’re out of a job. And as the saying goes, if you don’t use ’em, you lose ’em. For every week in bed, you lose about 1% of your bone density, making your bones more brittle and easy to fracture. That’s why astronauts, who often go for months without gravity, exercise for at least two hours a day and load up on calcium. In that same week, you also lose 1% of your muscle mass, particularly in your thighs, butt, and shoulders, which you’re no longer using. Now, normally, those muscles would suck sugar from your blood for energy to function, but after just 10 days of bed rest, this process slows down. The result? All of that unused sugar can build up in your bloodstream and lead to Type 2 diabetes. By week two, you can start developing nasty ulcers called bedsores. These form when the bony parts of your body, like your hips, tailbone, and ankles, press against the same spot for too long. The constant pressure blocks blood flow, killing your skin cells. And if you’re not careful, they could even rip through layers of skin and tissue and expose your bones and muscles, which sounds like the opposite of relaxing. Meanwhile, those muscles are wasting away faster than ever. After just two weeks, you’ve lost a whopping 10% of your muscle mass. And that causes a new problem, because the less muscle you have, the less oxygen, and therefore blood flow, they need. So, after a month in bed, your heart pumps 30% less blood per beat. And with less oxygen circulating through your body, you feel more tired. Even though you’ve been resting for a solid month. And if you don’t get up soon, well, you’re going to have a hard time ever getting up again. Because six months, maybe a year in, most of your muscles have wasted away. Your bones are too weak and fragile to bear your weight, and your heart isn’t strong enough to do much work anytime soon. Meanwhile, your brain isn’t a happy camper either. After all, you’ve been stuck in the same room for months. Staring at the same walls, the same spot on the ceiling, having the same experiences day after day. Not great for mental health, to say the least. A study of pregnant women found that bed rest increased their risk of anxiety and depression, and some women reported feeling isolated, out of control, and imprisoned. So, no, a year of uninterrupted bed rest is not the relaxing paradise we’d all dream it’d be. And this is exactly why doctors try to get their patients up and walking as quickly as possible. In the meantime, medical staff turn people every two hours to keep bedsores at bay and encourage them to do exercises in bed to get their heart and muscles working. So, just keep in mind: There’s nothing wrong with a lazy Sunday morning, as long as you’re up and moving before Monday strikes.