With seasonal affective disorder (SAD), a person's depression becomes worse with certain seasons, usually winter.

A person affected by SAD may have a low mood and be less interested in their daily activities. They may also sleep more and become less active.

Symptoms may begin as the days get shorter during autumn and become worse during December, January and February, before improving in the spring.

People of any age including children and young people can have SAD, which is thought to affect around 2 million people in the UK.

A less common form of SAD occurs in the summer and begins in late spring or early summer and ends in autumn. But in general, seasonal affective disorder starts in autumn or winter and ends in spring or early summer.

What causes seasonal affective disorder?

Hormones manufactured deep in the brain automatically trigger attitudinal changes at certain times of year. Experts believe that SAD is related to these hormonal changes. One theory is that reduced sunlight during autumn and winter leads to reduced production of serotonin in the brain. Serotonin is a neurotransmitter that has a soothing, calming effect. The result of there not being enough serotonin is feelings of depression along with symptoms of fatigue, carbohydrate craving, and weight gain.

SAD usually starts in young adulthood and is more common in females than in males. Some people with SAD experience very mild symptoms and feel out of sorts or irritable. Others have debilitating symptoms that interfere with relationships, productivity, and activities of daily living.

Because the lack of enough daylight during wintertime is related to SAD, it is seldom found in countries within 30 degrees of the Equator where there is plenty of sunshine all the year round.

What are the symptoms of seasonal affective disorder?

People with SAD have many of the usual symptoms of depression, including:

• Decreased levels of energy
• Difficulty concentrating
• Fatigue
• Increased/decreased appetite
• Increased desire to be alone
• Increased need for sleep
• Weight gain/ weight loss

How is seasonal affective disorder diagnosed?

It is very important that you do not diagnose yourself. If you have symptoms of depression, see your doctor for a thorough assessment. Sometimes, physical problems can cause depression. But at other times, symptoms of SAD are part of a more complex mental health problem. A health professional should be the one to determine the level of depression and recommend the right form of treatment.

How is seasonal affective disorder treated?

There are different treatments for SAD, depending on the severity of the symptoms. Many doctors recommend that patients with SAD try to get outside as much as possible during the day-time to increase their exposure to natural light. If this is impossible because of the dark winter months, exercise, antidepressant medication, cognitive behavioural therapy (CBT), light therapy (phototherapy), or a combination of these may help.

What Parents Can Do

Talk to your doctor if you suspect your child has SAD. Doctors and mental health professionals make a diagnosis of SAD after a careful evaluation and a checkup to ensure that symptoms aren't due to a medical condition that needs treatment. Tiredness, fatigue, changes in appetite and sleep, and low energy can be signs of other medical problems, such as hypothyroidism, hypoglycemia, or mononucleosis.

When symptoms of SAD first develop, parents might attribute low motivation, energy, and interest to an intentional poor attitude. Learning about SAD can help them understand another possible reason for the changes, easing feelings of blame or impatience with their child or teen.

Parents sometimes are unsure about how to discuss their concerns and observations. The best approach is usually one that's supportive and not judgmental. Try opening the discussion with something like, "You haven't seemed yourself lately — you've been so sad and grouchy and tired, and you don't seem to be having much fun or getting enough sleep. So, I've made an appointment for you to get a checkup. I want to help you to feel better and get back to doing your best and enjoying yourself again."

Here are a few things you can do if your child or teen has been diagnosed with SAD:

• Participate in your child's treatment. Ask the doctor how you can best help your child.
• Help your child understand SAD. Learn about the disorder and provide simple explanations. Remember, concentration might be difficult, so it's unlikely your child will want to read or study much about SAD — if so, just recap the main points.
• Encourage your child to get plenty of exercise and to spend time outdoors. Take a daily walk together.
• Find quality time. Spend a little extra time with your child — nothing special, just something low-key that doesn't require much energy. Bring home a movie you might enjoy or share a snack together. Your company and caring are important and provide personal contact and a sense of connection.
• Be patient. Don't expect symptoms to go away immediately. Remember that low motivation, low energy, and low mood are part of SAD — it's unlikely that your child will respond cheerfully to your efforts to help.
• Help with homework. You may have to temporarily provide hands-on assistance to help your child organize assignments or complete work. Explain that concentration problems are part of SAD and that things will get better again. Kids and teens with SAD may not realise this and worry that they're incapable of doing the schoolwork. You may also want to talk to the teachers and ask for extensions on assignments until things get better with treatment.
• Help your child to eat right. Encourage your child to avoid loading up on simple carbohydrates and sugary snacks. Provide plenty of whole grains, vegetables, and fruits.
• Establish a sleep routine. Encourage your child to stick to a regular bedtime every day to reap the mental health benefits of daytime light.
• Take it seriously. Don't put off evaluation if you suspect your child has SAD. If diagnosed, your child should learn about the seasonal pattern of the depression. Talk often about what's happening, and offer reassurance that things will get better, even though that may seem impossible right now.