Feel bad about feeling bad? Don't.

Studies done at the University of California, Berkeley, have found that acknowledging a blue mood — and not berating yourself for it — can help you work through it more easily.

It turns out that accepting negative emotions is better for your long-term mental health than constantly passing judgment on yourself, which can cause your feelings of negativity to snowball.

Putting pressure on yourself to feel upbeat can make you feel even more downbeat, according to the research. It turns out that the people who let feelings like sadness, disappointment and even resentment run their course had fewer mood disorder symptoms than people who judged themselves for having them or who tried to bury them. Accepting negative emotions seems to help you better cope with your stressors.

There's one important caveat, however. While it helps to acknowledge the normalness of negative emotions and not think you can — or need — to feel happy 24/7, it's also important not to ignore a persistent and deep blue mood, and other signs that could signal depression.

Symptoms of depression include a loss of interest in things that you used to enjoy, and deep feelings of worthlessness and hopelessness that last for three or more months. Unlike a blue mood, depression needs treatment, such as counseling, medication or both.

Other key signs of depression:

• Deep sadness
• Lack of energy or overwhelming fatigue
• Difficulty concentrating
• Thoughts of suicide
• Not sleeping or sleeping too much
• Loss of or marked increase in appetite
• Irritability