High expectations.Stress.Loneliness.The weeks from Thanksgiving through New Year’s can be especially difficult for people dealing with mental illness. In most cases, symptoms of the “holiday blues” are temporary, but they can turn serious, and if they last for more than two weeks can lead to clinical anxiety, depression or both.According to a recent survey, the National Alliance on Mental Illness found that approximately one-quarter of people with a diagnosed mental illness said the holidays make their condition “a lot” worse.