What is SAD and how common is it?
Many of us might feel happiest in the summer and a little fed up and lacking in motivation during winter. This is understandable as the weather is cold, there are fewer hours of sunlight, and the run up to Christmas can be stressful. However, for some of us the winter months can lead to a significant period of depression. This is relatively common with around one in 15 people feeling depressed between September and April, so-called ‘Seasonal Affective disorder’ (SAD).
What are the symptoms of SAD?
SAD is a cyclical mood difficulty where depressive symptoms are felt at the same time each year, most commonly in winter. This typically involves:
- Wanting to withdraw from spending time with others
- Feeling lethargic and lacking in motivation
- Difficulties in sleeping
- Eating more or less than usual
- Feeling down or hopeless
- Experiencing more negative and even suicidal thoughts
What can cause SAD?
Interestingly, SAD is more common among people who live in countries furthest from the equator. This could be due to less sunlight hours during the winter and longer days during the summer months. It makes intuitive sense that the change in season with less daylight hours leads to lower serotonin levels. Serotonin is a brain chemical that affects our mood, and the more we have the happier we feel. This can in turn affect levels of melatonin in the body, which impact on sleep patterns and mood.
In general, more antidepressants are prescribed during winter/Christmas. This could also be in part because our behaviour may change, with less time spent outdoors socialising and exercising, causing us to feel more lethargic and eat more ‘comfort food’. You might also be more likely to develop SAD if you have a family history of depression/SAD. SAD is also more likely to occur alongside an existing Major Depression or Bipolar Disorder.
How is SAD diagnosed?
A psychologist, psychiatrist or GP will be able to help you determine if you are experiencing SAD. It is important for you to record patterns you notice in your mood and energy levels across several months.
7 tips to support your mood this winter
1. Hack your serotonin with food
While nutrition can’t cure SAD, it can help stabilise mood and energy. Registered nutritionist Zara Hiridjee says it all starts with serotonin production.
“Serotonin is synthesised from the amino acid tryptophan, found in foods like eggs, turkey, salmon, tofu and nuts,” she explains. “But tryptophan has to cross the blood-brain barrier, where it competes with other amino acids. If you eat protein alone, the competition is high, and relatively little tryptophan gets through. Pairing it with complex carbohydrates – say, scrambled eggs on wholegrain toast, or salmon and quinoa salad – it changes the balance of circulating amino acids, allowing more tryptophan to enter the brain.”
2. Feed your gut and balance your blood sugar
About 90% of serotonin is produced in the gut, so a diverse diet matters. “Aim for 20-30 different plant foods per week to encourage the gut bacteria to produce short-chain fatty acids and neurotransmitter precursors that can positively influence mood,” says Hiridjee. “That includes beans, lentils, nuts, seeds, vegetables and wholegrains. Adding fermented foods like kefir or sauerkraut also supports healthy bacteria.”
Blood sugar stability is equally important. “If you start the day with something high in refined carbohydrates, say a croissant or white toast, you’ll get a rapid glucose spike, followed by a sharp dip,” Hiridjee warns. “That dip can trigger fatigue, irritability, cravings and even anxiety-like symptoms. To avoid that rollercoaster, meals should combine complex carbohydrates, protein and healthy fats like oats with Greek yoghurt, berries and nuts; or a wholegrain wrap with hummus, vegetables and chicken. Fibre is critical too, it slows digestion, feeds the microbiome and supports more stable energy release.”
3. Prioritise vitamin D and other key nutrients
From October to March in the UK, the body can’t make vitamin D from sunlight. “Low vitamin D is linked to fatigue and low mood,” says Hiridjee. “I recommend most people start with a safe daily dose of 10micrograms (400 IU), though some people may benefit from more depending on their individual needs.”
Omega-3 fatty acids from oily fish like salmon or sardines also supports brain cell function, while B vitamins (particularly B6, folate and B12) are crucial for neurotransmitter pathways. Magnesium, zinc and iron contribute to resilience against fatigue and low mood, too.
4. Step outside for light and movement
Light is the most powerful external cue for our circadian rhythm, our body’s internal clock. With changes in light exposure, this impacts our body’s melatonin production, meaning that our sleep/wake cycle is disrupted.
“This can affect your mood due to changes in our energy levels and ability to concentrate,” explains Rotaru. “Sunlight exposure on the skin produces that Vitamin D, that plays an active role in brain health and serotonin activity.”
Outdoor light is many times stronger than indoor lighting, even on a grey day. “Even aiming for 30 minutes of daily exercise, five days a week can help to uplift mood,” says Dr Semiya Aziz, GP and founder of Say-GP. “Outdoor activities provide the double benefit of encompassing both movement and exposure to light, which in turn can limit SAD symptoms.”
It doesn’t have to be vigorous: even daily short walks, stretches or gentle activity can help to lift energy.
5. Brighten mornings with light therapy
Light therapy is one of the most evidence-based interventions for SAD. Special lamps, delivering at least 10,000 lux, mimic daylight and can reduce symptoms when used for 20-30 minutes each morning.
“Start using a SAD lamp in early autumn, before symptoms peak,” advises Dr Aziz. “Make sure you choose a lamp specifically designed for SAD with the standard kite mark and not just any old lamp. Always check with your GP first about SAD lamps, especially if you suffer with eye problems, medical conditions or take certain medications.”
Some people also find dawn-simulating alarm clocks, which gradually increase light in the bedroom, useful for regulating sleep.
6. Reset your body clock with routine
Sleep disruption is a common feature of SAD. “Routine is key,” says Dr Aziz, who recommends:
• Going to bed and waking up at the same time daily.
• Avoiding screens for at least an hour before bed.
• Keeping the bedroom cool, dark and quiet.
• Limit caffeine intake after 12pm and avoid alcohol near bedtime.
• Create a calming routine like reading, stretching, warm shower or listening to a podcast.
Lifestyle changes can make a big difference, but sometimes professional help is necessary. Aziz stresses: “See your GP if symptoms are severe, if they interfere with your daily life, or if you feel hopeless or have thoughts of self-harm. It’s also important to rule out other causes such as thyroid issues or vitamin D deficiency.”
Treatment options include light therapy, medication and talking therapies such as Cognitive Behavioural Therapy (CBT). “BT therapists support their client to re-engage with activities that are meaningful and have a positive impact, create and maintain a routine as well as challenge any negative thinking,” Rotaru adds.
Small changes now can build resilience for months ahead. As Hiridjee puts it: “There’s no single superfood or shortcut. It’s about consistent patterns – Mediterranean-style eating, daily daylight, steady routines. Together, these create a buffer against the winter slump and help protect your mood.”
When should I speak to my doctor?
If you are considering light therapy or, if symptoms are severe, antidepressants speak to your GP. You can be referred or self-refer for support around depression in your local NHS Wellbeing Service, or seek out a private clinical psychologist.
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This article was reviewed on 27th October 2022 by Tracey Raye.
Dr Laura Keyes is a clinical psychologist, registered with the Health and Care Professions Council (HCPC) and British Psychological Society (BPS). She runs a private practice offering psychological therapy and assessments for neurodiversity to children and adults in Bedfordshire: drlaurakeyes.com
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