About one in 10 Americans experience depression at any given time, according to the Centers for Disease Control and Prevention. But many people with depression don't even know they have it.

Depressive symptoms may range from mild to severe and they can vary greatly. The signs of depression are often attributed to fatigue, stress, or the aging process.

Here are seven subtle signs of depression you shouldn't ignore.

1. Irritability.

Most people think depression leads to overwhelming sadness. But sometimes, people with depression experience anger and irritability rather than hopelessness and misery.

If you've noticed increased irritability -- or the people around you feel like they need to walk on eggshells -- don't ignore it. And don't blame your impatience and anger on your high stress level or increased work load. Instead, take a moment to consider the possibility that you may be depressed.

2. Sleep difficulties.

While the occasional restless night or two isn't necessarily a cause for alarm, persistent sleep difficulties could be a red flag. Insomnia can be a symptom of depression. Many people with depression struggle to fall asleep, or stay asleep, despite feeling exhausted.

Other people with depression sleep too much. They struggle to wake up in the morning and can't wait to go to bed at night. They often take naps during the day as well. If your sleep habits have changed, it's important to address the possible underlying reasons why.

3. Aches and pains.

There's an incredible link between your body and your mind. When you're struggling with mental health issues, you're likely to experience physical problems.

Many people are tempted to dismiss unexplained aches and pains as part of the normal aging process. But back pain, headaches, and sore muscles can be signs of depression.

4. Decreased energy.

Depression can zap your energy and cause you to feel lethargic and tired most of the time. But many people excuse their exhaustion by saying, "Well, I haven't been sleeping lately," or "My heavy workload causes me to be tired all the time."

Consider how your energy level may have shifted over time. If small tasks tire you or take longer to complete, you may be depressed.

5. Feelings of guilt.

Unnecessarily blaming yourself for the events in your life isn't healthy. If you feel guilty about everything from your divorce to that fight you got into as a kid, you may be depressed.

Many people with depression also feel worthless. Pay attention to your inner monologue and if it's overly harsh and critical, it could be a sign of depression.

6. Reckless behavior.

People who look like party animals on the outside are often suffering from depression on the inside. Frequent gambling, risky sexual behavior, and substance abuse may be attempts to mask unpleasant emotions.

If you've started indulging in new risks lately, it could be a sign that you're trying to cope with your inner turmoil. Unfortunately, these types of unhealthy coping skills will only provide momentary relief. They can make depression worse in the long-term.

7. Concentration problems.

If you're struggling to stay focused, and you feel like you're in a fog, it could be a sign that you're depressed. People with depression are often forgetful and they frequently misplace everyday objects, like their keys or paperwork.

Although today's digital world means most people are a bit distracted, concentration problems may also stem from mood disorders. If you've noticed a decline in your productivity or you're having difficulty staying on task, consider the possibility that you may be depressed.

What to do if you think you may be depressed.

If you think you may be depressed, talk to your doctor right away. Depression is very treatable. Therapy, medication, or a combination of the two can help reduce your symptoms.

Published on: Oct 6, 2015