SERIOUSLY SAD.

There's nothing wrong with feeling hummed out from time to time. Everyone does. It's natural part of being human, especially when you're pushing into your teen years. But how can you tell if you're just down in the dumps or truly livin' a world of depression?

No doubt about it, it's not easy being blue. But consider for a second what life would be like if you never had the lows that make you appreciate the highs. Close your eyes and imagine it. Your so-called best bud asks your longtime crush out, he says yes, and you feel... cheerful? You bomb that surprise quiz in biology...and think, "Gee, this will really help my average"? You have a huge fight with your mom over how messy your room is and you're... elated at an excuse to get that Martha Stewart subscription? We don't think so! But how do you know when you (or a bud) is not just having a big bummer of a week--but honestly depressed? We get tons of letters from readers baffled by the serious issue of depression. By answering your questions, we hope to clear up the confusion.

When I'm feeling lousy and crying for no reason at all, how can I tell if it's because of depression or just PMS?

Hey, hormones are chemicals. And during puberty, your body's hormones are constantly on the move. They're changing, increasing, decreasing or just plain doing whatever they feel like. But all of this affects your emotions.

Each month, before you get your period, the number of hormones in your body increases, causing you to be more emotional than usual. But even when you're not having your period, those chemicals are still doing the Mambo #5. Given all the changes that are going on, it's no wonder girls feel moody, irritable and lonely. One minute you're sobbing enough to fill your sister's kiddie pool and laughing like a hyena the next. This isn't depression--it's normal. Maybe not fun, but normal nonetheless.

Bottom line? Don't worry too much if you feel like you're riding the emotional equivalent of Space Mountain.

I only get bummed on weekends, when I should be having fun. What's wrong with me?

Take solace in knowing that it is not at all uncommon for teens to feel crummy on Sundays.

Why Sundays? Think about how you usually feel on Fridays. The weekend is coming... no school, fun stuff to do, and you can sleep in! You're psyched, right? Some people see Sundays in just the opposite way. Sundays mark the end of the weekend--the party's over. Ugh, tomorrow is Monday.

You can also get bummed around the end of summer vacation or the end of a holiday. While people like to joke about school being a drag, it helps your mood to change your overall outlook on your week. Don't just live for the weekends. Start looking forward to the special things that each day brings--even if it's just a compliment from the tennis coach on your serve or tater tots at lunch.

The seasons and the weather also contribute to your mood. Now that it's late fall, the sky is gray and everything looks dead. You've got to stay inside, so that means you can't even enjoy what little sunlight there is. Near the center of the brain is a gland that is affected by light. Researchers believe that significant decreases in sunlight can lead you to feel down and dreary, just like the weather! Make it a point to walk outside and soak up what little sun there is.

What is the deal with depression? Does being stressed mean I'm depressed?

Depression can happen to the most popular girl in school. Some depressed girls appear smart, pretty and confident on the surface, only dealing with their real feelings once they are alone. Depression isn't picky. Anyone can become depressed--millions of teens suffer from this disease. It's also possible that just like you inherited your dad's dimples, you may have a gene that makes you more depression-prone.

But how you cope with life's hard knocks plays a part, too. Sometimes, stuff happens that you have little or no control over. Potential traumas include Fluffy getting hit by a car, your folks filing for the big D, changing schools, moving to a new home, being teased, finding out your crush doesn't dig you and fighting with a friend...just to name a few. Any type of unwelcome change in your life can stress you out. (But being stressed doesn't mean you're depressed.)

While you can't control certain bad things from happening, you can control how you deal. Take Tanya. Tanya tries out for the soccer team but doesn't make the cut. Should she a) let herself feel bummed for awhile; talk about her emotions, fight negative thoughts like, "I'm not good at anything" and make a decision to join a ceramics class instead?

Or b) beat herself up with her own putdowns; bottle up her emotions by not talking about it; and continue to go watch soccer practices, which make her feel worse?

If you're more of a B-type kinda gal, you're at greater risk of being depressed. Focus on improving how you deal with upsetting stuff. Try not to kick yourself in the butt over every little thing. We know some things that seem little may be big to you, but the more times depression occurs it creates a greater chance that it will happen again.

Am I depressed if I feel bummed out a lot? What do I look for?

You can't know for absolute certain if you have depression until you get a diagnosis from a doctor. But real depression is about more than just feeling sad, crummy or dreary. Real depression affects your whole body--especially how you feel, think and act.

Depressed people hit low points a lot more than people who are just bummed out. Depressed people have bad feelings a lot of the time. What kind of bad feelings? Girls who have depression overwhelmingly feel sad, angry, guilt-ridden, anxious, hopeless, lonely, empty, worthless or simply numb. These feelings are intense--and last for most of the day. Girls who have depression commonly have bad days every day for at least two weeks or more.

How you feel is strongly connected to how you think. If your feelings are mixed up because of depression, then your thoughts will be too. Girls who are depressed have trouble remembering, concentrating or making decisions. If you're feeling depressed, your thoughts will be mostly negative, exaggerated or just plain untrue. You might think and believe nobody loves you, everything is your fault, that you're not a good person and don't deserve to be happy, or even that you'd be better off dead.

As a result of all the inner turmoil, things that used to be fun aren't anymore to a depressed person. Also watch for changes in appetite, excessive crying, shutting down, avoiding friends and family, getting in trouble at school, sleeping a lot or not being able to sleep at all. Even doing a simple thing like getting up in the morning can be incredibly difficult for a depressed person.

If I think my friend or I might be depressed, what do I do?

The most important step, and sometimes the hardest, is to admit you need help and ask for it.

If you suspect a friend is depressed and confront her, she may deny it or become angry with you. But if she truly needs help, you might have to reach out for her. Tell an adult you can trust.

Jackie, 13, remembers how her English teacher "kept asking if everything was all right. I guess I always looked like something was bothering me. I was scared and told her everything was OK when it really wasn't. One day, I bursted out crying over a project I had left at home. My teacher tried to calm me down but I ended up just blurting everything out. It was such a relief to finally tell someone besides my cat."

Keep reminding yourself that depression is nothing to be ashamed or embarrassed about. Don't let depression trick you into thinking that you can fix things on your own. You'll feel better a whole lot faster once you get help. Depression only gets worse when you don't do anything about it. Even if the depression is severe and has been going on for a long time, treatment for depression works.

What happens next? How is depression treated?

Just like the symptoms of depression vary from person to person, so does treatment. Your first step is to get a physical by your family doc to make sure the symptoms aren't related to some other problem.

Once you've ruled out other problems, your doctor can give you resources to find a professional who's right for you--someone who is able to determine if you're depressed and can provide the necessary treatment. The type of treatment you need depends on your symptoms, but could include medication or psychotherapy or a combination of both.

Does having depression mean someone is a psycho?

No girl (or guy) should feel like she must suffer alone and in silence for fear of being labeled "mental." Depression is a medical problem, like the flu or diabetes, except it affects the brain.

Believe it or not, your brain has other jobs besides crunching numbers for algebra class or analyzing Lord of the Flies. One of the biggies is balancing your feelings, thoughts and behavior. It does this by using chemicals that send and receive messages to and from the brain. It's a lot like instant messaging inside your head. If you have depression, these chemicals get mixed up. There might be too many, too few, or they might be going in all the wrong directions. That's why you need a professional to help decipher it all.

Depression isn't anyone's fault and doesn't mean you're an emotional wimp. The best news? Depression is treatable. You just need to take that first, important step-asking for help.

What can I do to ward off the blues? How can I help myself feel better after a really hard day?

There are a slew of things you can do to improve your mood and stay healthy through life's ups and downs.

Start with regular exercise. Working out releases special chemicals in your body that make you feel more energized and less sluggish. Even small amounts of activity help. Turn on the music and jump around, or take Buster for a walk.

Cut down on the amount of foods you eat that have a lot of fat, sugar or caffeine. The fatty foods make you feel weighed down, and sugar gives you a short energy boost but soon makes you feel more tired than before. Same with caffeine. And for a mood-boosting snack, try sunflower or pumpkin seeds. These treats contain a natural antidepressant chemical.

When you're feeling bummed out, the solution is not to keep your feelings bottled up. You'll only feel more desperate until one day, when you can't take it anymore, you'll erupt like a volcano. Make a dedicated effort to confront your feelings and release them in healthy ways-talk to a friend, write in a journal, draw, or send e-mail to a close friend or help center. Some girls even find praying or meditating helpful.

Learn to step away from the problem and relax once in a while. Take a short nap, put on your Walkman and listen to music, lie on the grass and stare at the sky, pet your cat, take a bath. Don't isolate yourself, but getting away occasionally is good. Just remember family and friends are good, too.

If you feel yourself getting bored and blue, go have some fun. Be with other kids, and don't forget the power of laughter. Join a club, rent a funny movie, and be good to yourself. Don't confuse boredom and blues.

If you do find yourself getting down, practice putting positive thoughts in your mind. Learning to be more optimistic will help you feel better about yourself. Keep practicing until good feelings become second nature and you begin to strengthen your outlook.

If it turns out your doc says you do suffer from real depression, realize you are doing a great thing for yourself by getting help. Getting down and out once in a blue moon is absolutely normal, but no one should have to face a life of constant sadness. Reach out for the help you need, and soon all your days will be a whole lot better.

A CRY FOR HELP

Depression can be so painful that sometimes dying seems the only way out. Each day, about 18 teens take their lives because they feel so helpless. Many girls worry about friends they think could be considering suicide. What are some of the warning signs? Anything that seems like a goodbye, like if a friend is giving away special belongings. Look for weird behavior that makes her seem almost too happy. And pay attention if a friend starts taking dangerous risks. Even talking about, writing about or drawing images of death and suicide should be taken seriously. It's really important to pay close attention to what a depressed friend is doing. If you pick up on any of these signals from a bud, you cannot handle it yourself! Your job is to get your friend help by telling a trusted adult what is going on. Don't wait another minute.