As the days grow shorter and sunlight becomes scarce, many people begin to notice subtle (or not-so-subtle) changes in their mood and energy. This annual shift is more than just a winter slump—it could be a sign of Seasonal Affective Disorder (SAD), a type of depression that follows a seasonal pattern, typically beginning in late autumn and lifting in spring. While winter can be a beautiful and cozy time for some, others struggle to maintain their usual motivation and outlook. But what exactly causes SAD, and how can we ease its effects?

Understanding Seasonal Affective Disorder

SAD is linked to changes in light exposure, which can affect the body’s internal clock (circadian rhythm), serotonin levels, and melatonin production—all of which play a key role in mood regulation and sleep. Reduced sunlight can disrupt these systems, leading to symptoms such as persistent low mood, fatigue, changes in appetite (particularly carb cravings), difficulty concentrating, and social withdrawal. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), SAD is considered a subtype of Depressive with a seasonal pattern.

The Science Behind Light and Mood

Light plays a crucial role in regulating our biological rhythms. When we’re exposed to natural light, the brain reduces melatonin (the hormone that makes us sleepy) and boosts serotonin (the hormone associated with mood and well-being). During darker months, this balance can be thrown off. A 2005 study in the Archives of General Psychiatry found that light therapy—exposure to bright artificial light—can significantly improve SAD symptoms, often within just a few weeks.

Signs You May Be Experiencing SAD

Persistent sadness or low mood that begins in late autumn and improves in spring
Oversleeping or finding it difficult to get out of bed in the morning
Increased appetite, particularly for sugary or starchy foods
Feeling sluggish or low in energy most days
Withdrawing from social interactions or losing interest in activities you usually enjoy

Strategies for Coping with the Winter Blues

Light Therapy
Using a light therapy box that emits cool-white fluorescent light can mimic natural sunlight. For best results, sit near the box for 20–30 minutes every morning. Always consult with a healthcare provider before starting light therapy, especially if you have a history of bipolar disorder or eye conditions.
Maximise Natural Light Exposure
Make the most of available daylight. Open blinds, trim overhanging branches near windows, and sit closer to windows when indoors. A morning walk—even on a cloudy day—can help reset your circadian rhythm and boost mood-enhancing hormones.
Establish a Winter Routine
Structure and routine can help counteract the sluggishness associated with SAD. Set regular wake-up and bedtimes, plan enjoyable activities, and avoid long stretches of unstructured time, which can increase feelings of isolation or hopelessness.
Exercise Regularly
Physical activity, especially outdoors, can improve mood and reduce anxiety. A 2013 meta-analysis published in The Cochrane Database found that exercise is effective in improving symptoms of depression, including SAD. Even 30 minutes of brisk walking a few times a week can help.
Consider Vitamin D Supplementation
Some studies suggest a link between low vitamin D levels and depressive symptoms. During winter, people in colder climates often don’t get enough sunlight to maintain adequate vitamin D levels. A simple blood test can check your status, and supplementation may help—but speak to a doctor first.
Stay Connected
While the instinct may be to hibernate, maintaining social connection is key to emotional well-being. Whether it’s a phone call with a friend, a cozy dinner, or a group class, shared moments can lift mood and help combat the loneliness that often accompanies SAD.
Try Talk Therapy
Psychological support can help individuals identify and shift unhelpful thinking patterns and behaviours. It’s especially useful for managing the anticipatory dread that some people feel as winter approaches.

Small Shifts, Big Impact

Coping with SAD doesn’t require overhauling your life. It often begins with small, intentional changes that gently lift your mood and support your well-being through the darker months. Whether it’s soaking up the morning sun, starting a light therapy routine, or reconnecting with loved ones, each small action can help ease the weight of winter.

Seasonal Affective Disorder is a real and valid mental health condition—but it’s also treatable. By learning to recognise its signs and proactively supporting your mind and body, you can move through winter with more light, energy, and hope.

References

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

Cooney, G. M., Dwan, K., Greig, C. A., Lawlor, D. A., Rimer, J., Waugh, F. R., ... & Mead, G. E. (2013). Exercise for depression. Cochrane Database of Systematic Reviews, (9), CD004366. https://doi.org/10.1002/14651858.CD004366.pub6

Lam, R. W., Levitt, A. J., Levitan, R. D., Enns, M. W., Morehouse, R., Michalak, E. E., & Tam, E. M. (2006). The CAN-SAD study: A randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder. American Journal of Psychiatry, 163(5), 805–812. https://doi.org/10.1176/appi.ajp.163.5.805

Wehr, T. A., & Rosenthal, N. E. (1989). Seasonality and affective illness. American Journal of Psychiatry, 146(7), 829–839. https://doi.org/10.1176/ajp.146.7.829

Seasonal Affective Disorder (SAD): How to Cope with the Winter Blues