27 Nov 2021

EXPLAINER: What is Seasonal Affective Disorder? All you need to know...

Laurann O'Reilly's column in this week's Nationalist

Six top nutrition tips for boosting your immune health with Laurann O'Reilly

Laurann O'Reilly

As the days get shorter and the weather gets a little chillier, it’s totally natural to occasionally feel a bit low and maybe a little sluggish.

However, some people can really fear the onset of the changing seasons, which can be accompanied by a significant change in mood and even anxiety in what is known as ‘Seasonal Affective Disorder’ or ‘SAD’.

Know that you are not alone.

Here, nutritionist Laurann O’Reilly and owner of Nutrition by Laurann, guides us through what SAD is and some lifestyle and nutrition strategies to get you through the winter months.

- What is Seasonal Affective Disorder? “Seasonal affective disorder (SAD) is a biological and mood disorder with a seasonal pattern.” (Frontiers in Psychology Journal). It can often involve a significant change in mood and in some cases feelings of anxiety which can have a huge impact on quality of life.
Whilst SAD can begin at any age it typically starts between the ages of 18-30 years. According to the HSE, it affects approximately 7% of the population.
SAD is also more likely to happen in females than males which according to the University of Utah is due to an oestrogen and vitamin D connection.

- What Causes SAD? There are a few different factors that may cause of SAD, which may include imbalances in mood-regulating brain chemicals, a lack of vitamin D (due to a lack of sunlight) and an overproduction of the sleep-regulating hormone melatonin.

1) Overproduction of Melatonin: Melatonin is a hormone responsible for regulating sleep and increases in the body as our days get darker, naturally preparing us for sleep.
With the shorter days this can cause people with SAD to feel a little more tired, affecting our circadian rhythm (body clock)

2) Imbalance of Serotonin: Serotonin is a neurotransmitter (or brain messenger) otherwise known as the ‘happy hormone’ and is involved in the regulation of our mood. Unfortunately, a reduction in daylight has been linked to a drop in our serotonin levels, which can result in low mood or depression with seasonal patterns. This is because sunlight stimulates special areas in the eye which triggers the release of serotonin.
3) Reduction of vitamin D: As our bodies produce vitamin D from sunlight, our levels of this vitamin can seriously decrease during the dark winter months. It has also been suggested that this drop in vitamin D may be linked to SAD as vitamin D is involved in regulating the production of serotonin. The Irish TILDA study also found that individuals over the age of 50 years are 75% more likely to experience depression if their vitamin D levels are low.

- Common Symptoms
Depression (mood shifting with seasons)
Feelings of stress, anxiety, tearfulness or sadness
Feeling tired or fatigued
Trouble Sleeping or Sleeping too much
Lack of energy and concentration
Lowered immune system

- Changes in Eating Patterns: Changes in our mood can also result in changes in our eating and research has found that “SAD patients tend to consume significantly larger dinners, more evening snacks during weekdays and weekends and exhibit a higher frequency of binge eating, external eating, and emotional eating”. It’s also been found that those with experiencing SAD have “more cravings for starch-rich food and food with high fibre”. (Frontiers in Psychology Journal)

- Therapies: Treatments for SAD may include medications and talk therapy (such as Cognitive Behavioural Therapy or CBT) as well as exercise and eating a healthy diet. Note: If you’re experiencing symptoms of depression that are disruptive to your daily life, please contact your GP who can support and find the best strategy for you

- Technology: Can play a role with 1) SAD lamps or Light Bulbs: In some cases, can also help improve melatonin production as they help to simulate daylight or 2) Silent Night Alarm Clock: This clever alarm clock helps to wake you up in a gentle and more natural way. The 18 White LED's start building up the light in the room 30 minutes before the alarm goes off, until they are at full brightness at the time the alarm goes off, again simulating daylight

How To Naturally Support Your Mood During the Winter Months
Your diet can play a key role in helping to relieve symptoms. Not alone can food make us feel good, but it can also help to nourish and support the body, whilst influencing appetite and mood.

- Omega Fatty Acids: As almost 60% of the brain is made of fatty acids, omega 3 fatty acids play an important role in maintaining healthy brain and nerve function. Tip: Aim for 2-3 portions of oily fish/week (salmon, mackerel, tuna, herring, and sardines), as well as walnuts, chia seed and flax seed (or oil). Recommended Supplement: If choosing a supplement, for therapeutic effects, opt for an omega-3 supplement with a high ratio of EPA:DHA such as Solgar Omega 3 Triple Strength

- Include a range of good quality lean protein: Your body makes feel-good neurotransmitters such as serotonin from protein foods so ensuring a steady supply is vital if you’re feeling low. Food Sources: high-quality protein such as lean meat, fish, nuts, seeds, beans, chickpeas and lentils.

- Bananas: Who knew, the innocent banana would come up on this list? As it turns out bananas contain an amino acid (protein building block) called ‘tryptophan’ which is essential for creating serotonin (the happy hormone) and also melatonin (the sleep hormone), thus having positive benefits for both mood and sleep! Tip: As the sugar from bananas is quickly released you can balance this out by having it on wholegrain brown bread, topped with a little cinnamon.
- Avoid The Sugar: Whilst you may crave sugary foods such as sweets, chocolate or biscuits when you feel low or sluggish, it’s best to avoid them if possible. High sugar foods result in spikes and crashes in blood sugar levels which affect our energy levels and mood and may deplete essential brain nutrients. Tip: Instead opt for wholegrain foods such as brown bread, pasta and rice which nourish the body, stabilise blood sugar levels and improve our digestion

Avoid Processed Foods – Recent studies suggest that some mood disorders may be linked to inflammation and that a greater consumption of foods associated with inflammation such as trans fats and refined carbohydrates which are found in processed and take away foods may also have an effect on our mood. Tip: It can be helpful to check the labels of your food, long ingredient lists can often indicate that foods are more processed. Also be aware of the cheaper vegetable oils as they are often high in ‘trans-fat’ mentioned above, instead opt for extra virgin olive oil and coconut oil for cooking.

- Gut Instinct: Often referred to as the ‘second brain’ our gut contains billions of receptors and messengers which send messages to our brain and almost 90% of your serotonin is produced in your gut. Our gut bacteria also send messages to the brain which can impact our stress responses. Tip: To keep your gut healthy try to include foods such as probiotic yogurt, fermented foods such as kefir, sauerkraut, and kombucha. It may also be helpful to take a course of probiotics, particularly if you have recently been on antibiotics (it generally takes about 3 months for the gut bacteria to re-balance). Recommended Supplement: Udo’s Super8 Microbiotic

- The B Vitamins: These play an important role not only in helping the body create energy but also in regulating the nervous system and the production of serotonin. Food Sources: Dairy products, eggs, lean meats, chicken, fish (tuna, mackerel, and salmon), wholegrain foods, dark green leafy vegetables, beans (kidney beans, black beans, and chickpeas), soya products, citrus fruits, bananas and nutritional yeast. Recommended Supplement: Sona B Vitamin Complex

Vitamin D: In addition to playing a role in mood, Vitamin D also has additional benefits which include supporting our immune health. Recommendation: the current recommendation is that the entire Irish Adult population should take a supplement of 20-25 μg/day or 800-1000 IU/day, my preferred one is the Pharma Nord Vitamin BioActive D Pearls which come in 1520 IU and 3000 IU.

- Magnesium: Known as ‘nature’s natural sedative’, magnesium plays an important role in regulating our stress response, recovery, repair and sleep. Studies have also found magnesium to be effective for mild to moderate depression in adults. Food Sources: Wholegrain foods, oats, bananas, broccoli, dark leafy green vegetables, nuts, seeds and soybeans. Recommended Supplement: Pharma Nord BioActive Magnesium

Choline: Although neither classified as a vitamin or a mineral, this nutrient plays an important role in the production of the neurotransmitter (cell messenger) acetylcholine which promotes mood and improves memory. Food Sources: Beef, chicken, fish, dairy products, mushrooms and beans. Recommended Supplement: Solgar Choline Supplement

- Zinc: Essential for brain and nerve development and can assist in balancing GABA, the anxiety regulating messenger. Studies have also found that supplementing with zinc results in improved mood and brain function. Food Sources: Red meat, liver, eggs and wholegrain foods. Zinc again can be taken in supplement form which should be available in most pharmacies and health stores. Recommended Supplement: Pharma Nord BioActive Selenium & Zinc

- Selenium: Plays an important role in the brain and nervous system, improves brain function as well as regulating dopamine (happy hormone). Food Sources: Lean meat, poultry, fish, dairy products, eggs, brazil nuts and wholegrain food. Recommended Supplement: (see zinc above)

- Hydration: With the weather getting a little cooler and the heating being turned on, it’s important to stay hydrated. Aim for 35ml x kg body weight of water per day. Tip: Why not purchase a reusable BPA free water bottle and keep it topped up and with you, whether you’re at your desk, in the car or working out.

- Get Moving (Preferably Outdoors): Exercise results in the release of endorphins (dopamine and serotonin) linked to reward and happiness, so where possible exercising outside can help with improving your mood.
Getting out in the daylight hours can provide you with a little sunshine (when we’re lucky) whilst also reaping the benefits of exercise.
Remember whilst nutrition can play a role but if you feel that you’re struggling during the winter months please contact your GP who can support and provide you with assistance.

For further information contact Laurann at or see

Laurann O’Reilly is a qualified and experienced nutritionist with a BSc. Degree in Human Nutrition from University of Nottingham and a Master’s in Public Health Nutrition from University College Dublin.

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