As daylight hours become shorter in parts of the world, health experts are drawing attention to seasonal affective disorder (SAD), a form of depression associated with changes in seasons. The condition can affect mood, energy levels, sleep patterns and daily activities, particularly during periods when people receive less natural sunlight.
Seasonal affective disorder is more than a temporary feeling of sadness or tiredness. It is a recognised form of depression that typically develops during particular seasons, most commonly in autumn and winter. Symptoms may include persistent low mood, loss of interest in usual activities, increased sleep, changes in appetite, difficulty concentrating and reduced energy.
Although the exact causes are not fully understood, experts believe reduced exposure to natural light can disrupt the body's internal clock, also known as the circadian rhythm. Changes in sunlight may also affect the regulation of melatonin, which influences sleep, and serotonin, a brain chemical involved in mood regulation.
The condition was first described in 1984 by Dr Norman Rosenthal, a researcher at the US National Institutes of Health, who introduced the term seasonal affective disorder. Since then, researchers have continued to investigate how changes in daylight influence the brain and emotional well-being.
Light therapy offers one treatment option
Light therapy is among the most widely recommended treatments for winter-pattern SAD. It involves sitting near a specially designed light box that produces bright light, helping compensate for reduced exposure to natural sunlight.
Dr Paul Desan of Yale University's Winter Depression Research Clinic recommends using a light box providing 10,000 lux for approximately 30 minutes every morning. However, experts caution that not all products marketed for seasonal depression provide sufficient brightness. People considering this treatment should seek medical advice before purchasing or using a device.
Medication and psychological support can also help
Antidepressant medication is another treatment option for people experiencing seasonal affective disorder. Doctors may recommend medication alongside light therapy, depending on the severity of symptoms and individual medical needs.
Cognitive behavioural therapy (CBT), a form of psychological treatment, can also help people recognise and change negative thought patterns associated with depression. Research suggests that its benefits may last longer than those of light therapy alone for some patients.
University of Vermont researcher Kelly Rohan has highlighted the value of this approach in helping people develop healthier responses to seasonal changes and overcome patterns of social withdrawal and negative thinking.
Everyday habits can support mental well-being
Alongside professional treatment, health experts recommend maintaining a regular sleep schedule, spending time outdoors during daylight hours and remaining physically active. Even walking outside on cloudy days can provide exposure to natural light.
Maintaining social connections is equally important. Planning enjoyable activities, meeting friends and avoiding prolonged isolation can help people remain engaged with their daily routines during difficult periods.
Experts also encourage people to recognise the difference between temporary seasonal changes in mood and clinical depression. Persistent sadness, loss of interest in everyday activities, changes in sleep or appetite and difficulty concentrating should not be ignored.
Although seasonal affective disorder is associated with particular times of the year, it is a treatable condition. Recognising the symptoms early and seeking appropriate medical support can help people manage its effects and maintain their quality of life.