It’s no secret that teenagers can be moody, but research shows that ongoing moodiness often is far more serious. Dr. Janna Gewirtz O’Brien, a Mayo Clinic pediatrician, said teen depression is much more common than most people realize.

“This is something that affects teenagers of all walks of life, of all backgrounds, and actually of ages from as young as 12 — sometimes even younger — and up to the young adult years,” O’Brien said.

She said new guidelines suggest screening all teens for depression starting at age 12.

“About half of kids are not identified with depression when they have it in the primary care setting, so we need to make sure that we’re catching more of those,” O’Brien said. “We can do better.”

She said parents also should look for these five signs that their teen is depressed:

1. Excessive irritability or generally depressed mood.

2. Trouble sleeping or excessive sleeping.

3. Sudden severe weight gain or weight loss.

4. A sudden drop in grades in school.

5. Sudden loss of interest in activities they used to enjoy.

“So if somebody reaches out to you, an adolescent reaches out and says: ‘I’m worried. I’m depressed. Or I’m thinking about harming myself,’ that is something to be taken very seriously,” O’Brien said.