VOCABULARY:

1. Insomnia - ba medical condition in which a person finds it very difficult to sleep

2. Diagnose - to identify an illness or the cause of a problem

3. Insecurity - anxiety about or a lack of confidence in oneself

ARTICLE:

Sometimes called "winter depression," seasonal affective disorder (SAD) is usually experienced as the days get colder and darker — often starting in autumn, with symptoms improving in spring.

However, the UK's National Health Service (NHS) notes that some people may experience SAD in summer, with their mood improving in winter. Whatever time of the year it starts, symptoms may be mild in the beginning, getting worse as the season continues.

As it is a form of depression, those who experience SAD will generally have many of the usual symptoms. These may include low moods lasting most of the day nearly every day, as well as losing interest in activities they normally like, and possibly a loss of concentration.

The US National Institute of Mental Health (NIMH) says those who experience SAD in winter may also report sleeping more than usual, overeating, and even wanting to avoid friends, family and social events.

Summer SAD symptoms may include insomnia, a poor appetite and increased anxiety.

NIMH also says that to be diagnosed with SAD, the periods of depression should take place around the same time of year, for at least two years in a row.

It is not entirely known what causes SAD. The Mayo Clinic says that multiple factors could play a part. For example, reduced sunlight in winter could decrease serotonin — a brain chemical that affects mood.

And Stephen Buckley from UK mental health charity Mind told Patient.info that longer daylight hours in summer can affect people's quality of sleep, making them feel low. Also, dressing for hot summer weather may make insecurities around body image worse.

SAD also seems to be more common among people who live further north or south of the equator, where seasonal daylight hours vary more.

Treatment for SAD may include doctors prescribing talking therapies and/or medication. Light therapy is also used sometimes — using a bright light to make up for reduced sunlight in winter.

Doctors may also recommend exercising more and getting out in the sun as much as possible.