Depression

Depression is the most undiagnosed ailment of the elderly population. (Don't take my word for it - do a search online for depression in the elderly.)
It isn't always expressed as sadness.
Sometimes you will see anger and/or irritability.
Some people don't eat. Others want to eat all the time.
Some people sleep more - others, less.
Some people withdraw from the people around them. Others have an unending list of ailments and complaints.
There are simple tests that can be done to determine signs and symptoms of depression. Staff observations are often crucial.
It is expected, that there will be a period of adjustment in a new setting, like a nursing home. But, when the mood affects quality of life, there are interventions needed.
Moving into a nursing home means there are new things added to the losses that we all have in our lives - loss of autonomy, privacy, giving up your home, your belongings, the pattern of your life. Sometimes it means giving up a beloved pet.
It may require someone like a licensed clinical social worker coming in to listen to your loved one. Sometimes medication is needed. Some doctors order a psychiatric consult (that doesn't mean their patient is crazy).
The important thing is to find the right combination of interventions, and help the resident feel better, and more in control of their lives.
It doesn't mean the nursing home is the wrong place to be. It means your family member needs help and support to cope.
Depression is not a "normal" part of aging.