Seasonal Affective Disorder: Symptoms, Causes and How to Support Your Mental Health
- Nicole Child
- Sep 27
- 6 min read
As the leaves turn, nights draw in, and September gives way to cooler, darker days, many of us notice a shift. For some, that shift is mild. For others, it triggers something more serious: Seasonal Affective Disorder (often shortened to SAD).
Understanding what it is, why it happens, and what you can do now to protect your mood and wellbeing can make a HUGE difference.
What is Seasonal Affective Disorder?
Seasonal Affective Disorder is a mood condition tied to the changing of seasons, typically in autumn and winter when daylight hours decline. (Although I know a few clients who say they actually get it in the summer months, but that’s something for another blog post!).
People with SAD experience depressive symptoms that come and go in these seasons. These symptoms can include:
Persistent anxious, ‘empty’ or low mood,
Feelings of sadness, hopelessness or pessimism
Low energy, fatigue or feeling lethargic
Irritability, frustration or restlessness
Changes in appetite or weight (often craving carbohydrates)
Sleep issues - oversleeping (hypersomnia) or struggling to stay asleep
Difficulty concentrating or daytime drowsiness
Struggling to keep to a morning routine
Increased sensitivity to social rejection
Social withdrawal or feeling the need to ‘hibernate’
Lacking interest in, or lost enjoyment of, activities
Physical pains and aches with no obvious physical cause
Thoughts of death or suicide
The Difference Between Seasonal Affective Disorder and the Winter Blues
Many people go through short periods when they feel sad or unlike their usual selves. Sometimes, these mood changes begin and end when the seasons change. (Think September: we have colder months, a return to school, college or University, and usually less time outside etc…).
But Seasonal Affective Disorder goes beyond simply feeling a bit down or sad when the weather changes. Often, these mood changes are more serious and can affect how a person feels, thinks, and behaves.
People with seasonal depression tend to follow the same pattern each year, feeling depressed during the fall and winter, or less commonly, spring and summer, but feeling well the rest of the year. If you’ve experienced this pattern for at least two years in a row, it’s possible you may have seasonal depression.
How Common is Seasonal Affective Disorder?
SAD is thought to be more common in countries further from the equator, where seasonal changes in daylight are more pronounced. Unfortunately for us, that includes the UK, where long, dark winters can take their toll.
The NHS estimates that around 2 million people in the UK experience seasonal affective disorder each year, with roughly 12 million affected across northern Europe.
Women in their 20s to 40s are about twice as likely as men to develop SAD, and younger people in general – particularly teenagers and those in their 20s and 30s – often report greater seasonal mood changes.
Why Does Seasonal Affective Disorder Happen?
The Neuroscience behind it
Research into seasonal affective disorder is ongoing. Although scientists are still trying to pinpoint the specific reasoning behind it, it is thought that reduced exposure to sunlight may play an important role. To help you understand why SAD can affect us so deeply, here are a few key scientific points:
Circadian Rhythm Disruption

Our body clock (circadian rhythm) depends heavily on light cues. When daylight hours shrink, the signals that tell our brain when to wake, generate energy, and produce certain neurotransmitters etc. get dampened. This can lead to sleep problems, fatigue, and feeling mentally foggy.
Melatonin & Serotonin Imbalance

Melatonin is the hormone that helps regulate our sleep-wake cycle and how we respond to darkness. When the nights grow longer, the body may produce more melatonin, leaving us feeling drowsier and less energetic. Serotonin, on the other hand, is a neurotransmitter linked to mood and well-being, and reduced exposure to sunlight is associated with lower serotonin levels. Together, these shifts are thought to play a key role in the emotional symptoms of SAD.
Brain Adaptations

Studies into how the brain changes with the seasons show that our sensitivity to light and the activity of certain brain regions shift throughout the year (Zhang et al, 2023). This means the brain itself responds differently as daylight hours increase or decrease. How strongly someone feels these changes can depend on things like genetics, past experiences with depression, or even how far they live from the equator. Together, these factors help explain why SAD can feel so intense and difficult to manage for some people.
Immune & Physiological Effects

When sunlight exposure drops, vitamin D levels can fall, which has been linked to both reduced mood regulation and weaker immune function. On top of that, people often move less during the colder months, while changes in diet and disrupted sleep patterns can add further strain. Together, these shifts place extra pressure on the body and mind, leaving us feeling 'off' and more prone to low mood.
Why It Matters for Wellbeing, Mood & Performance
When SAD or seasonal mood shifts are not addressed, our wellbeing suffers in multiple ways:
Increased absenteeism or reduced effectiveness at work/study (due to low energy, difficulty concentrating)
More conflict or irritability in relationships or home life
Greater risk of depression, anxiety disorders and sleep disorders
Lowered immune resilience: people may get more colds, infections and feel physically run down
Even for people who do not meet diagnostic criteria for SAD, mild to moderate symptoms reduce quality of life. It’s a kind of ‘wear and tear’ on the nervous system and mood regulation.
So how is Seasonal Affective Disorder treated?
The National Institute for Health and Care Excellence (NICE) recommends that SAD be treated in line with other forms of depression. Talking therapies, such as cognitive behavioural therapy (CBT) or Solution Focused Hypnotherapy (SFH), are suggested, as they can help people develop strategies, build resilience and shift unhelpful thought patterns without relying solely on medication.
Alongside professional support, there are also practical lifestyle habits you can build into your routine. These small, consistent changes can work hand-in-hand with therapy to ease seasonal mood shifts and protect your wellbeing.
Wellbeing Habits to Support Seasonal Affective Disorder
The good news is that there are many habits, supported by science, that help buffer the effects of reduced daylight, colder weather, and mood drift.
Habit | The NeuroscienceBbehind Why It Helps |
Bright or natural light exposure in the morning | Light is the main cue for the circadian clock. Morning light helps suppress melatonin appropriately and reset your internal clock so you feel more awake, properly alert during the day. |
Have regular sleep/wake pattern | Consistency reinforces circadian rhythm. Going to bed and waking at similar times each day (even weekends) helps stabilise mood, lower stress, regulate hormones. |
Mindful, warm rituals before bed (e.g. dim lightening, hot bath, reading) | Helps shift brain/body from sympathetic (alert) state into parasympathetic ('rest & digest') state. Warmth helps drop the core body temperature, which signals sleep readiness. |
Vitamin D and nutritional support | Low vitamin D is associated with many mood disorders. Omega-3 and antioxidants support brain health and reduce inflammation which can exacerbate depressive symptoms. |
Sip a hot drink mindfully | Slows the nervous system, allows breathing to settle and present moment awareness helps reduce rumination, which fuels low mood. |
Observe changes in nature | Seasonality awareness helps us anchor in what is changing rather than create resistance. Exposure to green, autumn colours and the crisp air helps mood, increases serotonin. |
Breathwork and stress reduction practices | Practices like slow breathing reduces activity in the amygdala (the threat centre of the brain) and reduce cortisol levels. This helps with anxiety, improves ability to sleep. |
Limiting evening screens and blue light exposure | Screen lights - especially blue wave - suppresses melatoni and delays sleep onset, causing more fragmented sleep. Better sleep = better mood and mental clarity. |
Regular movement/gentle exercise | Physical activity increases mood modulators like endorphins, serotonin and BDNF (brain derived neurotrophic factor). Even walks after meals help digestion and metabolic regulation. |
Please don't put the pressure on yourself to do all these things! Pick 2-3 of these habits that appeal most to you and commit to them for 1 week and see how you feel.
Habits like these act as anchors. Anchors are small but steady steps that help you feel more grounded as the seasons change.
The challenge?
Knowing what helps and actually sticking with it are two very different things (especially when low energy or mood makes motivation harder to find).
That’s where Solution Focused Hypnotherapy comes in.
How Solution Focused Hypnotherapy Can Help with SAD
Solution Focused Hypnotherapy is an approach that focuses on resources, strengths, and what does work - rather than dwelling on what’s wrong.
When it comes to SAD or seasonal mood changes, here’s how Solution Focused Hypnotherapy can support:
Adjust mindset and expectations – Solution Focused Hypnotherapy helps you notice small wins, shift from 'this always knocks me out' to 'I have tools, I can respond differently.'
Anchor positive habits more deeply – Through hypnosis, you can embed intentions and positive habits with greater ease.
Reduce anxiety and rumination – Hypnotic techniques can help calm the threat systems in the brain, reduce overthinking, and ease sleep anxiety.
Support emotional regulation – When mood dips happen, SFH gives you internal strategies to restore calm more quickly.
If you feel SAD or seasonal mood shifts are making your life harder, you don’t have to wait until winter gets worse. Working together, we can map out which habits will serve you best in your individual pattern, embed them reliably, and build up resilience.
If you want to find out more about how these wellbeing habits specifically apply to you, or how Solution Focused Hypnotherapy might help you move more smoothly through this autumn season, you can click here to contact me or enquire about sessions.