How do you feel when you hear that a friend or relative is in the hospital? A little nervous? Hoping that everything goes well and that your loved one will soon be home? Those are understandable reactions.

And what do you think when you hear that they've been sent home? That they're out of the woods now -- at least as far as any dangers associated with being hospitalized are concerned -- and you can stop worrying?

The facts suggest something different.

You may have heard that about 20 percent of the people age 65-plus who go home from the hospital end up being readmitted within 30 days.

In health care circles, this information led to much wailing and gnashing of teeth. The initial assumption was that patients just didn't take care of themselves when they got home - didn't take their medicine, didn't go to the doctor - and so relapsed, landing right back in the hospital a few weeks later.

The only problem with that assumption was that it didn't quite square with the facts.

If people were relapsing, you'd expect them to go back into the hospital for the same problem they were in for before: if they went in with heart failure, or for lung problems, you'd think that's what the issue was when they went back.

But according to a study published in the New England Journal of Medicine, that was the case only about a third of the time.

Two-thirds of the time, they ended up in the hospital with a new problem. If they first went in to the hospital with heart failure, perhaps they were readmitted with digestive system problems, or with a breathing problem, or with mental illness, or with injuries, or with any of a dozen other apparently unrelated problems.

Why?

It's no surprise that being hospitalized can be a shock to the body and mind. The actions taken in the hospital to save lives can also be both physically and mentally traumatic. Dr. Harlan Krumholz, writing in the New England Journal of Medicine, notes that besides having to deal with the illness or injury that put them there in the first place, "During hospitalization, patients are commonly deprived of sleep, experience disruption of normal circadian rhythms, are nourished poorly, have pain and discomfort, confront a baffling array of mentally challenging situations, receive medications that can alter cognition and physical function, and become deconditioned by bed rest or inactivity."

All of these things, he goes on to explain, can make it harder for people to function normally when they get home, can increase their risk of developing more problems, and can make it more likely that they'll make mistakes that can hurt them.

Consider just one of these issues, malnutrition.

One study showed that about 20 percent of people age 65-plus get less than half their minimum nutritional needs met while hospitalized. They may not be permitted food before tests or surgery, or may not feel like eating, or an arm or shoulder injury makes it hard to remove food wrappers or use knives and forks.

What difference does it make? Dr. Krumholz notes, "Malnutrition can affect every system in the body," making it harder for wounds to heal and for the heart, lungs, and digestive system to work properly, and increasing the odds of getting an infection or bed sores, among other problems.

And nutritional problems don't end when the individual leaves the hospital.

Eloise lost 12 pounds when she was in the hospital for brain surgery. After she was discharged, she said, "I went to stay with my brother and his wife and two boys. The grown-ups both worked and the boys were in school. I found that I couldn't open the refrigerator door, or open food packages, or press the button to open the microwave door to put food inside. I was too weak. I had to wait until my nephew got home from school and helped me before I could get any food."

When loved ones come home from the hospital, it is not enough to make sure that their kitchens are stocked. They may need more help than you would ever imagine to avoid a downward spiral resulting from malnutrition.