Millions suffer from rare summer SAD as heat worsens mental health.

As the first signs of summer appear, while others prepare their barbecues, Charlotte Pennington draws her blackout blinds tight, plunging her home into darkness. At just 26 years old and working as a debt specialist adviser, she admits that when she tells people she truly hates the summer, they struggle to believe her. For Charlotte, living in Lancashire with her partner Tyler, the warmer, brighter months bring a genuine physical and mental deterioration in her mood, sparking increased anxiety, sleeplessness, and a profound sense of unease that sometimes makes leaving the house a major struggle. She is suffering from a little-known condition: reverse seasonal affective disorder (SAD).

While the public is generally aware of winter SAD, where low light levels in autumn and winter disrupt hormones like serotonin and melatonin, affecting roughly 3 per cent of Britons annually, the summer variant is far more common than many realize. Clinical psychologist Adriana Kober of Priory Hospital Barnt Green notes that while 80 to 90 per cent of cases follow the traditional winter pattern, one in ten individuals with SAD experience symptoms during the summer. Despite this, the condition is frequently overlooked or dismissed by medical professionals. Charlotte recalls her own GP rejecting her claim of summer SAD, insisting the condition only applies to winter sufferers, leaving her without a formal diagnosis to this day.

Experts confirm that summer SAD is a recognized and treatable mood disorder driven by complex biological and psychosocial factors. Dr Jon Van Niekerk, chair of the faculty of general adult psychiatry at the Royal College of Psychiatrists, explains that while the condition is usually linked to darker periods, a smaller number of people suffer in the summer due to disrupted sleep patterns, altered circadian rhythms, heat, humidity, and excessive daylight. In some cases, too much light prevents the brain from producing sufficient melatonin, leading to insomnia and jet-lag-like symptoms that also impact mood regulation.

The symptoms of summer SAD differ significantly from their winter counterparts. While winter SAD often manifests as low energy, lack of motivation, increased sleep, and weight gain, the summer version presents with anxiety, irritability, insomnia, restlessness, reduced appetite, weight loss, and a heightened sensitivity to heat. The defining characteristic, according to Adriana Kober, is a clear, recurring change in mood, energy, and sleep that interferes with daily life, work, and relationships every year. Charlotte, who was diagnosed with anxiety and depression at age 13, began noticing this specific seasonal pattern at 16, reporting that her condition would suddenly worsen from around March and April. This condition underscores a critical reality: government directives and medical understanding must evolve to recognize these environmental triggers, ensuring that public health resources address the urgent needs of those whose well-being is compromised not by the cold, but by the heat and light of summer.

While many friends embraced the warm air and bright light, Charlotte felt overwhelming anxiety and avoided going out. She sometimes could not even attend college.

However, she noticed significant improvement in October. Entering autumn brought earlier sunsets and colder air, which made her feel much better.

By winter, her whole body seemed to decompress. She became suddenly happier within herself and enjoyed seeing other people and going outside.

Generally, winter Seasonal Affective Disorder is attributed to falling light levels. It can often be treated with very bright artificial light mimicking sunlight.

The exact trigger for summer SAD remains unknown. Increased light levels may contribute to disrupted sleep patterns.

Adriana Kober explains that light synchronizes circadian rhythms and regulates mood-stability hormones. Changes in daylight affect sleep, energy, and emotional balance.

Longer daylight hours may suppress evening melatonin production. This disrupts sleep cycles significantly.

Charlotte struggles with summer sleep because it is too bright and late before darkness arrives. She wakes regularly during the night.

These interruptions adversely affect her mental health and increase anxiety levels significantly. She feels ill and tired the next day.

This cycle continues for months. It spikes her anxiety and makes going outside really difficult.

Some researchers suggest an immune response to high pollen counts triggers summer SAD. A 2019 University of Maryland study linked high pollen days to worsening mood.

Another theory involves sensitivity to sunlight increasing stress hormone cortisol. People lack sufficient darkness to relax.

High temperatures might suppress thyroid function and related hormones. This slows us down, reduces motivation, and lowers mood.

Adriana Kober notes social factors also contribute to SAD onset. Travel, routine changes, work patterns, holiday financial pressures, and increased social expectations play roles.

Summer is associated with social activity, positivity, and physical confidence. This contrast between internal experience and external expectation intensifies distress.

Dr Jon Van Niekerk states SAD relates to disrupted sleep, circadian rhythm changes, heat, humidity, and longer daylight.

Existing mental health conditions are often involved. Anxiety disorders may find busy summer schedules heighten feelings of being overwhelmed.

Those with ongoing depression may experience more severe symptoms during seasonal transitions.

People with bipolar disorder often face heightened sensitivity to daylight shifts, where seasonal changes can destabilize mood. Adriana Kober notes that Seasonal Affective Disorder (SAD) rarely stands alone; it frequently overlaps with other psychological vulnerabilities. Currently, no summer equivalent exists for the light therapy used to treat winter SAD. Winter treatment involves therapy lamps emitting at least 10,000 lux of bright light to mimic natural daylight. Used for 20 to 30 minutes each morning, these lamps help regulate circadian rhythms and influence mood-related brain chemicals. These chemicals, such as serotonin and melatonin, often become disrupted during darker winter months. Clinical research confirms that consistent, correct use of light therapy effectively improves mood, energy, and sleep patterns. While cooling therapies have been theorized for summer SAD, they have never been tested in clinical trials. Cognitive behavioural therapy remains one of the most effective treatments for seasonal depression, including summer SAD. Adapted CBT helps individuals identify unhelpful thought patterns, build behavioral strategies, and develop essential coping skills. A 2015 study in the American Journal of Psychiatry tracked 177 adults with seasonal affective disorder. The research found that SAD-tailored CBT resulted in lower recurrence rates and better long-term outcomes than light therapy. Medication, particularly antidepressants, also proves effective for managing moderate to severe symptoms. Charlotte now takes antidepressants year-round but periodically adjusts them as temperatures rise. She strictly pulls down blackout blinds in the early evening to block sunlight. Charlotte has kitted out her entire house with these modifications to control light exposure. She avoids socializing until after 9pm when light levels naturally drop. She also wears tinted glasses during the day to further limit exposure to bright light. Two months ago, she discovered a Facebook group dedicated to people suffering from summer SAD. She found 800 others in the exact same situation, instantly ending her feeling of isolation. The group allows members to share feelings and anxieties about this real and miserable condition. Many members, like Charlotte, have expressed a longing for dark, grey days again.