Seasonal Affective Disorder (SAD): Understanding Seasonal Depression
Seasonal Affective Disorder (SAD) is a form of depression—often called seasonal depression or winter depression—characterised by a predictable, seasonal pattern of mood changes and other depressive symptoms. Most commonly, symptoms begin in late autumn or winter when daylight decreases and improve in spring as daylight increases. Less frequently, some people experience a summer-pattern variant in which symptoms intensify during the warmer months.
While many of the emotional, cognitive, and physical changes mirror those seen in major depressive disorder (such as persistent low mood and reduced interest in activities), the hallmark of SAD is its regular recurrence during specific seasons across multiple years. This temporal pattern suggests a strong connection between light exposure, the biological clock, and brain chemistry involved in mood regulation.
People with Seasonal Affective Disorder are thought to experience a light-triggered biochemical imbalance involving neurotransmitters like serotonin and hormones like melatonin. Shorter daylight hours can disrupt the body’s circadian rhythms—the internal clock that influences sleep, appetite, energy, and mood. As daylight wanes, melatonin production may increase and serotonin activity may decrease, contributing to sleepiness, carbohydrate cravings, and low mood. Geography matters too: prevalence increases at higher latitudes where winter days are shortest. In equatorial regions with abundant year-round sunlight, SAD is far less common. In Singapore, for example, experts note that consistent sunlight makes clinically significant SAD less likely, though individuals can still experience depressive episodes with other triggers.
Signs and Symptoms
Symptoms of Seasonal Affective Disorder align with depression and can range from mild to severe, affecting daily functioning at home, school, or work. Core symptoms may include:
• Feeling sad or persistently low in mood.
• Loss of interest or pleasure in previously enjoyed activities.
• Changes in appetite (often carbohydrate cravings) and weight.
• Changes in sleep (too much or too little).
• Fatigue, low energy, or feeling “slowed down.”
• Agitation or restlessness.
• Feelings of worthlessness, guilt, or hopelessness.
• Difficulty thinking, concentrating, or making decisions.
• Thoughts of death or suicide (seek urgent help if present).
Additional features in Winter-Pattern SAD often include: oversleeping, overeating, weight gain, and social withdrawal (“hibernation-like” tendencies).
Additional features in Summer-Pattern SAD may include: insomnia or reduced sleep, poor appetite with weight loss, agitation, anxiety, and in rare cases increased irritability or aggression.
Symptoms typically recur for at least two consecutive years during the same season and remit during other times of the year. If mood changes occur without a clear seasonal pattern, or last throughout the year, a clinician may consider other diagnoses.
Risk Factors
SAD sometimes runs in families, suggesting a genetic vulnerability. Individuals with a personal or family history of depression, bipolar disorder, or schizophrenia may be at higher risk. Biological contributors include reduced serotonin activity during darker months and overproduction of melatonin, which can heighten sleepiness and shift circadian timing. Vitamin D insufficiency—more likely when sunlight exposure falls—may also play a role in mood regulation. Environmental risk rises with distance from the equator due to shorter winter days. Lifestyle patterns that limit daylight exposure (e.g., long indoor hours) can compound the problem.
Causes and the Mind–Body Clock
The prevailing explanation centres on light and the circadian system. Light hitting the retina helps synchronise the suprachiasmatic nucleus (the brain’s master clock), which regulates melatonin and influences serotonin pathways related to mood. In winter, later dawns and earlier dusks can desynchronise this clock. A phase delay (feeling naturally “shifted later”) may lead to sluggish mornings, low energy, and delayed sleep schedules. Conversely, in summer-pattern SAD, excess heat, extended daylight, or other seasonal stressors may contribute to insomnia, irritability, and anxiety.
Diagnosis
There is no single lab test for SAD. A mental health professional evaluates symptom patterns, duration, severity, and functional impact across at least two consecutive seasons. The assessment rules out medical conditions (such as thyroid disorders), medication side effects, substance use, and other psychiatric diagnoses. Because depression can be serious, clinicians also assess for suicide risk and coexisting conditions like anxiety disorders, bipolar spectrum conditions, or circadian rhythm sleep–wake disorders. Keeping a brief mood-and-sleep diary across weeks can help document timing and triggers and guide tailored treatment.
Treatments
Effective care often combines several approaches based on symptom profile, preference, and response. Four commonly used interventions include:
✽ Light Therapy
Bright light therapy uses a medically approved light box (10,000 lux, UV-filtered) placed at eye level and an appropriate distance (often 30–60 cm). Typical protocols involve 20–30 minutes each morning during fall and winter. Morning sessions help shift the circadian clock earlier, improve alertness, and reduce depressive symptoms. Consistency matters: daily use for several weeks is usually needed before benefits are substantial. People with specific eye conditions or bipolar disorder should consult a clinician first to avoid adverse effects (e.g., eyestrain, headache, or mood switching in bipolar spectrum).
✽ Psychotherapy
Talk therapies, particularly Cognitive Behavioural Therapy (CBT), are well-supported. CBT for SAD targets seasonal thoughts (e.g., “winter is hopeless”) and behaviours (e.g., withdrawal and oversleeping), replacing them with adaptive routines (structured activities, pleasant events, outdoor daylight exposure). Behavioural activation—scheduling meaningful, mood-lifting activities—helps counter inertia. Mindfulness-based strategies and problem-solving skills can also ease rumination, stress, and sleep-disrupting worry.
✽ Anti-Depressant Medications
Selective Serotonin Reuptake Inhibitors (SSRIs) are commonly prescribed for SAD, either seasonally or year-round depending on recurrence and severity. Some individuals start medication preventively in early autumn to blunt winter symptoms. Medication choice, dose, and duration should be personalised and reviewed periodically to balance benefits and side effects. For people with bipolar disorder, medication plans must be coordinated carefully to reduce the risk of mood elevation.
✽ Vitamin D and Sunlight Practices
While vitamin D is not a standalone cure, optimising vitamin D status and seeking safe daylight exposure can support overall wellbeing. Practical steps include spending time outdoors in the morning, sitting near windows during daylight hours, or arranging workspaces to maximise natural light. In sunny climates like Singapore, regular outdoor time can be protective; sunscreen and sun-safety practices remain important.
Self-Help and Daily Strategies
Maximise morning light: Get outside soon after waking or sit near a bright window; pair this with a consistent wake time to anchor your body clock.
Keep a steady routine: Regular sleep and meal times stabilise circadian rhythms. Avoid long daytime naps that can fragment night sleep.
Move daily: Moderate aerobic activity (e.g., brisk walks) boosts energy and mood. Outdoor exercise multiplies light exposure benefits.
Plan pleasant events: Schedule social contact, hobbies, and manageable goals to counter withdrawal and increase positive reinforcement.
Fuel and hydrate: Emphasise balanced meals with vegetables, lean proteins, and whole grains. Watch for comfort-eating patterns that can worsen lethargy.
Wind down wisely: Create a low-light, screen-limited pre-sleep routine; keep bedrooms cool, quiet, and dark at night.
Track patterns: A simple mood/sleep/steps log helps you and your clinician identify timing, triggers, and what works.
When to Seek Professional Help
Reach out to a mental health professional if seasonal symptoms last most days for two weeks or more, interfere with daily life, or recur annually. Seek urgent help if you experience thoughts of self-harm or suicide. Early intervention can shorten episodes, prevent escalation, and build long-term coping skills tailored to your climate, routines, and health status.
Singapore Context
Because Singapore has abundant year-round sunlight, classical winter-pattern SAD is uncommon. However, people can still experience depressive episodes that worsen during certain months due to work cycles, monsoon-related routines, or reduced outdoor time. The same evidence-based approaches—CBT, structured daily light exposure, exercise, regular sleep, and when indicated, medication—can be adapted to individual circumstances. If mood dips are tied more to life stressors than daylight, psychotherapy focused on stress management, problem-solving, and behavioural activation may be especially helpful.
Frequently Asked Questions (FAQs)
Is SAD the same as “holiday blues”?
No. Holiday blues are often brief and situational. SAD follows a seasonal pattern across years, lasts weeks to months, and meets clinical criteria for a depressive episode.
How long until light therapy works?
Some people notice improvement within 1–2 weeks; others need 3–4 weeks. Use daily and at consistent times for best results; combine with regular sleep and outdoor activity when possible.
Can I prevent SAD?
If you have recurrent seasonal episodes, start preventive strategies in early autumn: establish a fixed sleep/wake schedule, increase morning daylight, begin light therapy (with clinician guidance), schedule exercise and social activities, and discuss preventive medication if prior winters were severe.
What if my symptoms occur in summer?
Summer-pattern SAD often features insomnia, reduced appetite, and agitation. Strategies may include earlier, dimmer evenings, cooling the bedroom, morning routines that avoid excessive midday heat, CBT, and a clinician-guided treatment plan.
Getting Support
If seasonal patterns affect your mood, concentration, sleep, or relationships, professional assessment can clarify what you’re experiencing and match you with effective, personalised care. Evidence-based treatments help many people recover fully each year and reduce the intensity of future episodes.
We recommend This Video to those who wants to learn more about Intellectual Disability.
About Us
We are a team comprising psychologists based in Singapore endeavouring our best to prioritise our clients’ needs. When you embark on this journey with us, we take a collaborative approach where you and your psychologist work closely together, and listen to what you have to say — No judgments, and in a safe space. Meet our Team
Quick Links
Contact Us
150 Cecil Street #07-02 S069543
Opening Hours
Monday to Friday: 8am to 6pm
Saturday: 8am to 2pm
Sunday: 10am to 2pm (Online only)
Admin Hours
Monday to Friday: 8am to 5.30pm
Saturday: 8am to 2pm
© Copyright 2023 – Psychology Blossom | Privacy Policy | Terms
