context: You're up. You're down. And you're soon up again. It seems like you spend your days riding an emotional roller coaster. Are these changes normal? The answer is "maybe" -- so long as they don't disrupt your life or the lives of people around you. Many things can affect how your mood shifts throughout the day. For example, because of body rhythms, most people feel upbeat and energetic around noon but tend to have more negative feelings during the early afternoon or evening. Sometimes, mood swings are a symptom of a mental illness. Or they could be a clue that something else is happening in your body. Serious mood shifts that threaten your well-being can be treated by medical professionals. Lifestyle changes can often help mild ones. But first, you'll need to figure out what could be causing your bumpy ride. Day-to-day hassles and unexpected surprises -- both the good kind and the unpleasant ones -- can definitely change your mood. And when you're especially sensitive, you may react more strongly or more often to situations than other people. Lack of sleep, a common complaint of people under stress, doesn't help. Some people feel uneasy, fearful, and worried even when they realize there's no good reason. You could be diagnosed with generalized anxiety disorder if you've had trouble controlling your worries more often than not for the past 6 months and you have additional symptoms such as trouble sleeping. When it's severe, it can be almost impossible to get through the day. People with bipolar disorder have highs and lows that are much more intense and longer-lasting than usual mood swings. For example, it's normal to feel great, like everything's going your way, for a day or two. Someone with bipolar disorder, though, can spend several days or weeks being the life of the party: racing around, talking fast, not sleeping much, and doing destructive things like running through the family's bank account. That's called a manic phase. They could possibly hear voices, too. Similarly, it's not uncommon to have trouble getting out of bed to go to a job you don't like. But someone with bipolar disorder may stay in bed for 4 days and lose that job. They may feel unmotivated, sad, or even suicidal. That is called the depressed phase. This treatable mental illness affects 3% of adult Americans each year. Someone who is depressed may have mood swings, too. They'll have their lows, then feel OK, but they won't get the manic highs that someone with bipolar disorder would. Depressed people may feel worse in the morning and become more cheerful later in the day. If you've been feeling sad, drained, restless, or hopeless for more than 2 weeks, it's time to call your doctor. A characteristic of this mental illness is sudden, intense shifts in mood -- such as anxious to angry, or depressed to anxious -- usually without the extreme highs seen in bipolar disorder. These are often "triggered" by what seem like ordinary interactions with other people. Someone with borderline personality disorder doesn't deal well with stress. They may want to harm themselves when they feel very unsettled or upset. Mood swings, a hot temper, and easily getting frustrated can sometimes be symptoms of ADHD in adults. If you have it, you're probably also restless, impulsive, and unable to focus. Sex hormones are tied to your emotions, so changes in your hormone levels can lead to mood swings. It's no surprise that teenagers are often described as "moody." For women, PMS, pregnancy, menopause (the year after your last period), and perimenopause (the years before it) can lead to unpredictable moods. Men's hormones tend to stay pretty stable until age 30, when testosterone begins to gradually decline. About a third of men age 75 and older have low levels of testosterone. That can cause mood swings, along with erectile dysfunction, sleep problems, and, yes, hot flashes. When your mood swings get in the way of your job, your relationships, or any other part of your life, make an appointment with your doctor to sort out what's going on. Simple changes may help you handle mild, uncomfortable, annoying (to you or to others) mood swings. Regular workouts -- even a daily walk -- can help take the edge off depression and anxiety, because they'll trigger your body to make feel-good endorphins. Plus, exercise can improve your sleep. Listening to upbeat music can influence your mood in a good way. Too much caffeine can give you symptoms similar to anxiety, so try cutting back and see if your emotions level off. Cognitive behavioral therapy is a type of short-term treatment. Your therapist will help you change patterns of thinking and behavior that add to problems in your life. For instance, if criticism sends you into a tailspin, you may work on new ways to receive and react to constructive feedback. Dialectical behavior therapy can help people with borderline personality disorder learn how to better control their anger and impulses and manage their dramatic mood shifts.