Seasonal Affective Disorder (SAD): Symptoms, Causes and UK Online Support

Seasonal Affective Disorder (SAD) is a recognised clinical type of depression that follows a seasonal rhythm. While many people in the UK talk about the 'winter blues', SAD is more significant than a temporary dip in mood. It typically begins as the days shorten in autumn and reaches its peak during the darkest winter months of December, January, and February.

According to the Royal College of Psychiatrists, SAD affects around 3% of the UK population. Because the UK experiences significant variations in daylight hours between summer and winter, residents are particularly susceptible to the disruption of their internal body clocks. While less common, a small number of people experience 'summer SAD', though the winter-onset variety is the most frequently diagnosed in British clinical practice.

The symptoms of SAD are very similar to those of Generalised Anxiety Disorder or Depression, but they essentially 'reset' when the seasons change. Patients often report a distinct shift in their behaviour and physical state. Common signs include:

• Persistent low mood: Feeling down, tearful, or hopeless for most of the day.
• Lethargy and sleep problems: Feeling exceptionally tired during the day and sleeping longer than usual (hypersomnia).
• Changes in appetite: A specific craving for carbohydrates and 'comfort foods', often leading to weight gain.
• Loss of interest: Finding no pleasure in hobbies or socialising that you usually enjoy.
• Irritability: Feeling easily agitated or 'snappy' with friends and family.
• Concentration issues: Difficulty focusing on tasks at work or following a conversation.

The exact cause is not fully understood, but NHS guidance suggests that the main theory involves the reduced exposure to sunlight during the autumn and winter. When light hits the back of the eye, messages are sent to the part of the brain that controls sleep, appetite, and mood.

The Role of Serotonin and Melatonin

Lower light levels can lead to several physiological changes:

• High Melatonin Levels: Melatonin is the hormone that makes you feel sleepy. In people with SAD, the body may produce it in higher quantities, leading to excessive lethargy.
• Low Serotonin Levels: Serotonin is often called the 'happy hormone'. Lack of sunlight can lead to a drop in serotonin, which affects mood and appetite.
• Circadian Rhythm Disruption: Your body uses sunlight to time important functions, such as when you wake up. Reduced light in winter can disrupt your internal clock, leading to the symptoms of SAD.

If you are diagnosed with SAD, the NICE (National Institute for Health and Care Excellence) guidelines recommend a range of treatments similar to those used for standard depression. These are often combined for the best results.

Light Therapy

Many patients find relief using a SAD lamp (light box). These device simulate exposure to sunlight. While not usually available on the NHS, they are a common self-care recommendation. You should look for a lamp specifically designed for SAD with at least 10,000 lux.

Talking Therapies

Cognitive Behavioural Therapy (CBT) is highly effective. It helps you identify negative thought patterns and develop coping strategies for the winter months. Counselling can also provide a space to discuss the impact of your mood on your life and relationships.

Medication and Vitamin D

In some cases, a GP may prescribe Selective Serotonin Reuptake Inhibitors (SSRIs) such as sertraline or fluoxetine. Additionally, the UK government recommends that everyone considers taking a Vitamin D supplement (10mcg) during the winter months, as low levels can contribute to fatigue and low mood.

Simple changes to your daily routine can make a significant difference in managing milder symptoms of seasonal low mood:

• Maximum Light Exposure: Try to get outside as much as possible, especially at midday and on bright days. Even a short walk during your lunch break can help.
• Home Environment: Sit near windows when you are indoors. Keep your work and home environments light and airy.
• Regular Exercise: Physical activity is known to boost mood-regulating chemicals in the brain.
• Stress Management: If possible, avoid planning high-stress projects during the peak of winter.
• Stay Connected: Social withdrawal is a symptom of SAD, but isolation often makes the depression worse. Even brief social interactions can provide a mood lift.

If your seasonal low mood is affecting your ability to work, maintain relationships, or perform daily tasks, it is time to seek professional advice. You do not need to wait until you are in a crisis to speak to a GP.

An online doctor can offer a confidential consultation from the comfort of your home—which is often helpful if you are feeling low on energy. During the appointment, the GP will ask about your symptoms, their duration, and how they impact your life. They can:

• Provide a formal assessment of your mental health.
• Discuss potential treatment pathways, including medication.
• Provide a private fit note (sick note) if your symptoms prevent you from working.
• Give guidance on Vitamin D and lifestyle measures specific to the UK climate.