Happy one moment, and extremely sad the next. Too many of us are familiar with this wavering of feelings. Mood swings!
I have the choice of being constantly active and happy or introspectively passive and sad. Or I can go mad by ricocheting in between. Sylvia Plath, American poet, novelist, and short story writer. Obviously, Plath is talking about mood swings here and its dangerous consequences.
Mood is a state of mind, an emotion, and it is natural to have different moods depending on what s going on in our life. When we are happy we ignore the negative events and when we are sad we can t find anything positive in our life. There is nothing wrong with mood swings, there is nothing wrong with going from one state of mind to another during the course of the day. The problem arises when we have an extreme response to events around us or within us. The mood swings are so rapid, they affect the quality of life. It is then that we suffer from mood disorder.
It is not exactly known why mood swings happen. Scientists believe mood swings maybe the result of chemical reactions, or rather, a chemical imbalance in the brain. Mood swings are generally accompanied with symptoms such as anxiety, changes in behaviour or personality, confusion, poor judgement, rapid speech, difficulty in concentrating and comprehension, forgetfulness, and even excessive consumption of alcohol.
Listed here are some probable causes of mood swings.
1. Hormonal changes
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You may remember having mood swings when you were a teenager, that aggression and then depression, being irritable most of the time, and being angry at your parents. Mood swings during teenage can be attributed to rapidly rising sex hormone levels. PMS is also a known cause of mood swings in teenage girls and adult women, and can be attributed to fluctuating levels of oestrogen and progesterone at the time of periods.
It is very common to have mood swings when you are pregnant, especially in the first and third trimester. It s a life changing event that brings with it emotional and physical changes that can cause physical stress, fatigue, excitement of being pregnant along with hormonal changes that affect the neurotransmitters that regulate mood. All of these can cause mood swings. Don t worry, it is absolutely normal. Menopause is another reason why you may experience mood swings. Decreased oestrogen levels is the culprit here. One theory indicates that low levels of oestrogen cause symptoms such as hot flashes and night sweats that lead to sleep disturbance, hence, the daytime mood changes. Another theory supports the view that mood swings are a response to altered roles and relationships associated with age-related life changes. Yet another theory propounds that you may experience mood swings when hormones (dopamine, serotonin) that regulate your mood and emotions are thrown off balance because of low levels of oestrogen. 
Mood swings due to hormonal changes are easily treatable. Your doctor will prescribe medicines based on your symptoms. Counselling and psychotherapy also helps.
2. Substance abuse and side effect of certain medication
Sudden mood swings or angry outbursts are often a symptom of drug abuse. If you are using drugs to escape from problems in your life, know that you are not only making the existing problems worse but creating more problems for yourself. All psychoactive drugs alter the way your brain functions. The drugs cause a surge in dopamine action in your brain triggering feelings of pleasure. Gradually, the brain adapts to the dopamine surges, it produces less dopamine thus decreasing dopamine s impact. Now, you take larger amounts of the drug to get the high. Long term abuse changes other brain chemicals as well. Glutamate, a neurotransmitter responsible for cognitive function, is altered by drug abuse, negatively affecting your learning and memory, behaviour control, and decision making capacity. 
Realizing that you have addiction problem is the first step to recovery. Don t downplay your problem. Seek support from your family and friends. That way you can lean on them for comfort and guidance. Do not hesitate to seek professional help.
It s not just substance abuse that can cause mood swings. Certain medication can give you mood swings as well.
Anti-depressants you are taking for your depression or bipolar disorder may not be right for you, since they can cause violent mood swings. Your doctor may put you on different medication in that case.
Some high blood pressure medication such as Lisinopril decrease sodium levels in the blood and increase the levels of potassium. This may cause depression and anxiety in some people. 
Although some trials reported that cholesterol lowering statins such as simvastatin cause mood disturbance, later studies found no mood swings side effects with simvastatin or pravastatin. But better to be aware!
Certain antibiotics such as gentamicin and ciproflozacincan cause mood changes in some people.
Ritalin used in treatment of ADHD is yet another medicine that can have mood swings as one of its side effects.
If you notice mood swings or depressive symptoms check with your doctor immediately. Don t stop the medication. Your doctor will decide whether to continue or discontinue the medicines.
Mood swings are most obvious in the mood disorders such as depression and bipolar disorder. Depression is when you have a persistent feeling of sadness, hopelessness, and dejection. It can be triggered by a chemical imbalance in the brain, or life events such as death of a loved one, suffering from an incurable disease, and loss of job.
The most common symptoms you may experience are
Mood swings, hopelessness, guilt
Loss of interest in activities you earlier enjoyed or loss of interest in friends and family
Delusional or hallucinating
Problems in concentration, memory, and decision making
Suicidal, withdrawing from people
Sleep changes, fatigue
Loss of appetite or overeating
Bipolar disorder is where you have depression alternating with more than one week periods of unusual high energy. You may find yourself being
Highly self-confident and optimistic
Aggressive and angry
Impulsive, showing poor judgement and reckless behaviour
Delusional and hallucinating
Depression or bipolar disorder is not something you can prevent or cause. Your chances of having these conditions increase if it runs in the family. You can just be aware of it and get it treated as soon as possible. Your doctor will chalk out a treatment plan for you. Basically, mood disorders are treated with psychotherapy and mood stabilizing drugs. You may be advised to join a support group too.
Whenever you are stressed, high amount of stress hormones is released into the bloodstream, where they travel to heart, lungs, stomach and other parts of the body (remember fight or flight response) and bring about changes such as heightened senses, rapid breathing, increased heart rate, energy surge, and change in brain functioning. Mild stress is actually beneficial as it improves your performance and cognitive tasks, but persistently high stress reduces hormonal balance leading to imbalance in the brain neurotransmitters. And neurotransmitter imbalance causes severe mood swings. Meditation, tai-chi, yoga, relaxation techniques are all good stress busters.  Even a long solitary walk can bring down your stress levels.
Notice how you reach out for that bar of chocolate or sugary foods whenever you feel low? Carbs boost your tryptophan levels, so more serotonin is synthesized in the brain. And serotonin is a known mood elevator! A hint: Choose healthy carbs instead of sugary foods, so that you can get other useful nutrients as well. Similarly, omega-3 fatty acids found in foods such as fatty fish, flaxseed, walnut, and soybean affect the neurotransmitter pathways in a positive way, elevating your mood. Deficiency of omega-3 is known to cause anger, irritability, and depression.
A study published in the journal PLOS indicates that there is a link between food and mood, and that could be the gut microbe. They worked with high fat diet and high sugar diet on experimental animals, and found that high fat diet changed the gut microbe and led to the development of depressive symptoms such as un-hedonic (inability to feel pleasure) behaviour, while high sugar diet too impacted the gut microbe but in the opposite way . So, don t disturb the gut microbe to save yourself from mood swings.
This goes to prove that a balanced diet is very important. Keep that in mind, next time you go dieting, especially diets that restrict to one macro-nutrient. Some diets also make you eat less and exercise more. That s a sure shot way to get cranky and have mood swings.
6. Medical conditions
Last but not the least, medical conditions such as brain tumour, stroke, dementia, meningitis, lung diseases, cardiovascular diseases, and thyroid problems could also cause mood swings. Talk to your doctor about your mood swings. Do not ignore your mood swings, else, they may give rise to serious mental and physical health problems.
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National Institutes of Health. Understanding Drug Abuse And Addiction. Drugabuse.gov. N.p., 2012.
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Swiger KJ, Manalac RJ, Blaha MJ, Blumenthal RS, Martin SS. Statins, Mood, Sleep, and Physical Function: A Systematic Review. European journal of clinical pharmacology. 2014;70(12):1413-1422. doi:10.1007/s00228-014-1758-y.
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