Seasonal Affective Disorder: The mystery behind the ‘winter blues’

Colours of grey flooding the sky, the frost within our icy winters and our dreary, rainy days - for many people, these have negative connotations and leave us feeling lethargic and of a low mood. When such feelings continue to persist over the entirety of the autumn/winter period - where days are much shorter and temperatures begin to fall - individuals can be seen to develop a condition referred to as ‘Seasonal Affective Disorder’ (SAD). 

So, let’s dive deeper into what SAD actually is! According to the NHS, individuals with SAD often experience symptoms similar to those of ‘normal’ depression. The main difference is that those with SAD experience their symptoms repetitively within a specific window of the year, occurring at the beginning of autumn/winter with a gradual improvement once we move into the spring calendar (NHS, 2021). With the NHS estimating that around two million people in the UK, and an increasing twelve million people across Northern Europe, are experiencing SAD every year, we must find ways to help reduce the effects and the severity of the disorder (Nuffield Health, 2021).

What are the symptoms of SAD to look out for?

• Persistent low mood

• Loss of pleasure and interest in routine activities

• Low self-esteem

• Reduced activity

• Lethargy

• Sleeping for longer

• Finding it difficult to concentrate

• Increased appetite, specifically craving foods of high carbohydrate content

  
  

It is particularly important to note that both the nature and severity of symptoms vary from person to person. In addition, some people experience these symptoms in distinct phases, alternating with periods of increased happiness, energy, and sociability. (NHS, 2021).

Why do some people suffer from SAD?

Currently, there are two neurological theories that attempt to explain why some individuals suffer with this disorder of periodic depression. 

1. Changes in serotonin regulation

The first theory revolves around people with SAD having difficulty regulating the neurotransmitter serotonin within their brain. Serotonin plays a significant role in balancing a variety of things such as mood, memory, appetite, and stress (Bamalan and Al Khalili, 2023). It has been discovered that dysregulated serotonin activity can play a role in the pathogenesis of conditions such as depression and anxiety, both of which are associated with symptoms of SAD (Bamalan and Al Khalili et al., 2023). 

To support this, a study concluded that people with SAD had 5% more SERT, a protein involved in serotonin transport within the brain, in the winter months as opposed to within the summer months (Melrose, 2015). So, what does this mean for those experiencing SAD? As SERTs act to help transport serotonin from the synaptic cleft back into the presynaptic neurone, a higher concentration of SERT in the brains of people with SAD suggests that they experience low serotonin activity. This is because increased concentrations of SERT allow for higher re-uptake of serotonin, lowering the availability of serotonin in the synaptic cleft for signalling. Therefore, the effects of serotonin are reduced (Melrose, 2015). 

High levels of sunlight during the summer months are predicted to naturally keep the concentration of SERT low. This helps explain why people with SAD show higher SERT levels in autumn and winter. As sunlight decreases, serotonin activity drops, and this seasonal reduction is even more pronounced in individuals with SAD (Melrose, 2015). 

Overproduction of melatonin

The second theory explains that people with SAD may have difficulty with the overproduction of melatonin within their body. Melatonin is a hormone produced by a secretory neuroendocrine organ known as the pineal gland, located within the middle section of the brain (Aulinas, 2022). It effectively responds to darkness outside, triggering sleepiness within an individual (Melrose, 2015). As winter days have reduced sunlight hours and it is darker for longer periods of time, melatonin production in people with SAD increases, leading to them feeling sleepy and lethargic. Whilst this theory has an impact on the symptoms of SAD, it does not directly explain why SAD occurs. 

A combination of both of the theories mentioned above - a decrease in serotonin levels and an increase in subsequent melatonin levels - directly impacts the circadian rhythms of individuals with SAD. Our circadian rhythm is the body’s internal clock which is specifically synchronised to respond to rhythmic light-dark changes that occur daily (when transitioning from day to night) as well as throughout seasons (where the duration of sunlight changes). People with SAD experience a circadian signal that is timed slightly differently in response to seasonal changes in day length, which confuses the body and makes it harder to adjust to these changes.

SAD in women

It has been found that SAD occurs four times more frequently in women than in men, with the age of onset generally between 18-30 (Melrose S, 2015). Within women specifically, hormonal fluctuations can make them a high-risk demographic for SAD, with a focus on oestrogen levels, that can directly affect serotonin levels (Soares and Zitek, 2008). This can involve the hypothalamic-pituitary-gonadal axis where reproductive hormones, such as oestrogen, have a high density of receptors in ‘mood centres’ of the brain such as the amygdala, the hippocampus, and the hypothalamus (Wharton et al., 2012).

How can we differentiate between a period of low mood and SAD?

Due to many of us experiencing some symptoms of SAD throughout autumn/winter periods, how are we able to differentiate between short periods of low mood and low energy or SAD? 

Speak to your GP

If, after reading through this blog, you are realising that you too might have developed SAD, please book an appointment with your GP to discuss your symptoms further. The NHS provides a series of psychological assessments to assess your mental health, such as asking you questions about your mood, lifestyle, seasonal changes in thoughts and behaviours, as well as your history of depression. A confirmed diagnosis may be reached if your depression is seen to occur within a similar time frame annually for at least two consecutive years, or if periods of intense depression are quickly followed by periods without depression (NHS, 2021). 

Actionable steps, with supporting biological facts, to help combat SAD

What can we to prevent, or combat, SAD? In the rest of this blog, I will be including some simple, fairly inexpensive ways, backed by science, that will help you to increase your mood, productivity, and overall happiness over the winter/autumn periods. Whilst these tips and tricks are tailored to those who suffer from SAD, it does not mean that you can’t start to incorporate these into your autumn/winter routine today to help prevent such feelings from ever occurring in the first place!

1. Obtaining increased sun exposure via SAD lamps

One way to combat the symptoms of SAD is through increased light exposure, which can be achieved artificially through devices known as SAD lamps which administer artificial light. In a recent study, a randomised small group of SAD patients were asked to use a lamp which administered bright, white light for a period of six hours per day, whilst a placebo patient group used a lamp for a similar time period that administered low 'yellowish' light. After 14 days of treatment, the individuals using the bright, white light experienced a significant improvement in their depressive symptoms compared to those within the placebo group (Østergaard et al., 2020). 

This particular method of treatment is more commonly referred to as phototherapy. It is an effective antidepressant treatment with minimal side effects and with measurable effects 1-2 weeks after starting treatment. Phototherapy is specifically associated with the modulation of serotonergic and melatonergic activity within the brain which, in turn, regulates an individual’s circadian rhythm and sleep (Kamara, 2022).

How can an artificial lamp combat the lack of natural sunlight during the day? This was my initial thought prior to researching the mechanism behind SAD lamps and the huge benefits they provide. So, let’s dive a little deeper into what SAD lamps are and if they actually work. As mentioned above, SAD lamps mimic natural sunlight by administering artificial bright, white light - they may also be referred to as a light box or light therapy. They are widely available at a range of price points and are not prescription-based pieces of equipment (Cleveland Clinic, 2024) - this means that anyone can readily purchase one to experience the benefits (I will link a few highly recommended SAD lamps at the end of this blog, in case you are interested in investing in one!).

It is very common to see improvements in mood after 2-4 days of using one for 30 minutes each day (with a 10,000-lux bulb), but they may not work for everyone! The most effective time of day is in the morning. SAD lamps differ from natural sunlight as they do not increase vitamin D levels but you also don’t need to worry about UV radiation (Cleveland Clinic, 2024)! 

During the summer, light exposure is greater earlier in the day, which helps to advance sleep, as opposed to light being administered late, as seen within autumn/winter periods, which results in delaying sleep. People with SAD experience issues with getting to sleep because of their circadian rhythm gradually delaying sleep onset, therefore causing them to sleep later in the day due to the variations in evening light levels. And so, when sleep is brought forward through the assistance of artificial light therapy, better synchronisation of sleep is achieved, resulting in an antidepressant effect in such individuals (Kamara, 2022).

2. SAD Diary

Another way to help combat the feelings associated with SAD is to keep a ‘SAD diary’. This involves keeping a diary, in written form or an online record, where you regularly note down your SAD symptoms, how your body is feeling, and what emotions you are experiencing at different stages throughout the day to act as regular check-ins (Kamara, 2022). In addition to this, ensure that each time you are noting down a certain feeling or bodily sensation that you note down the time and weather so that you might pick up on any external triggers or patterns to the symptoms you are experiencing. It may be easier to compile this information in an area such as the ‘Notes’ section on your phone so you are able to readily jot down anything relevant on-the-go too! 

3. Cognitive Behavioural Therapy (CBT)

Cognitive Behavioural Therapy (CBT) may be useful to combat the feelings associated with SAD. CBT is an abbreviation that is regularly thrown around in today’s society, but what does it really involve? CBT techniques help to replace negative thoughts with positive ones through a sub-technique referred to as behavioural activation, which helps an individual to identify their negative thoughts and their subsequent triggers whilst also recognising and identifying tasks that are particularly engaging to them (NCCIH, 2019). 

Why is this important for those suffering from SAD? There has been evidence that suggests that CBT reduces the recurrence, as well as the remission, in individuals suffering from SAD, specifically through behavioural activation (NCCIH, 2019). Behavioural activation is based on the idea that depression arises from a lack of response-contingent reinforcement - in other words, when positive outcomes no longer follow a person’s actions. This leads to low mood, social withdrawal, and further reinforcement of depressive behaviours, creating a self-perpetuating cycle (Quigley and Dobson, 2017). 

One task that you can start with limited resources is writing down your ‘to-do’ list for the week (Greater Manchester Mental Health NHS Foundation Trust, 2023):

• Separate your tasks into three sections: routine, pleasurable, and necessary

• Further separate these tasks, depending on how difficult they are for you to complete, into three additional sections: least difficult, medium difficult, and most difficult.

• Rewrite your plan for the week, making sure that you include at least one routine, one pleasurable, and one necessary activity from the ‘least difficult’ section. Within this, make sure that you have included what you are going to do within each task, where you are to complete it, and specifically when you are to complete it.

Whilst this may seem a simple task, it helps you to break the vicious cycle of negative emotions and behaviours seen in those with SAD by encouraging you to take control of your time - taking small but effective steps to feel more confident is getting you back to the old you again! 

Ultimately, Seasonal Affective Disorder is a real condition that can severely impact your mental health, wellbeing, and overall motivation to complete tasks within your regular routine. However, with the help of this blog and the additional resources that I have shared throughout, you are able to begin to understand the mechanisms behind SAD, as well as ways to incorporate small but effective changes into autumn/winter days that can help you say goodbye to the ’winter blues’.

Other Resources

It wouldn’t be a blog written by me if I didn’t include some podcast episodes to help support my research and advice to further allow you to effectively treat Seasonal Affective Disorder from the comfort of your home!

The first I would like to share is a podcast by the Manchester branch of the mental health and wellbeing charity, ‘Mind’, which explores a greater understanding of the disorder as well as incorporating some additional tips and tricks on how to combat these winter blues! Podcast and tips for help with Seasonal Affective Disorder (SAD) and the Winter Blues - Manchester Mind

The second podcast episode I would like to share is from ‘The Mel Robbins Podcast’ where motivational speaker and coach, Mel Robbins, discusses how her 15-minute morning routine has boosted her motivation and focus over time. This can be adopted to help regain focus and motivation over the autumn/winter periods in individuals with SAD. Try It For 1 Day: Do This Every Morning to Boost Motivation & Focus

Links to SAD lamps

Deng Jr Sad Lamp, 10,000 Lux Sad Light Therapy Lamp with 360° Effective Field, UV-Free Sun Light Lamp with Remote Control, Adjustable Colors/Brightness and Timer, Daylight lamp for Home/Office : Amazon.co.uk: Health & Personal Care    

Lumie® Mini | Compact 10,000 Lux Bright Light Therapy Lamp 

References

NHS (2021). Treatment - Seasonal Affective Disorder (SAD). [online] nhs.uk. Available at: https://www.nhs.uk/mental-health/conditions/seasonal-affective-disorder-sad/treatment/.

Melrose, S. (2015). Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression Research and Treatment, [online] 2015(1), pp.1–6. doi:https://doi.org/10.1155/2015/178564.

Kamara, F. (2022). Six self-help tips for seasonal affective disorder (SAD). [online] www.bupa.co.uk. Available at: https://www.bupa.co.uk/newsroom/ourviews/seasonal-affective-disorder.

Østergaard Madsen, H., PV Straszek, S., Kragh, M., Volf, C., Hageman, I. and Martiny, K. (2020). Lysbehandling af depression. [online] Ugeskriftet.dk. Available at: https://ugeskriftet.dk/videnskab/lysbehandling-af-depression [Accessed 27 Feb. 2025].

Cleveland Clinic. (2024). A Sun Lamp for SAD: Does It Work? [online] Cleveland Clinic. Available at: https://health.clevelandclinic.org/are-sun-lamps-best-to-improve-your-winter-mood.

NCCIH. (2019). Seasonal Affective Disorder and Complementary Health Approaches : What the Science Says. [online] Available at: https://www.nccih.nih.gov/health/providers/digest/seasonal-affective-disorder-and-complementary-health-approaches-science.

Quigley, L. and Dobson, K.S. (2017). Chapter 12 - Behavioral Activation Treatments for Depression. [online] ScienceDirect. Available at: https://www.sciencedirect.com/science/article/abs/pii/B978012803457600012X.

Bamalan, O.A. and Al Khalili, Y. (2023). Physiology, Serotonin. [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK545168/.

Kanen, J.W., Arntz, F.E., Yellowlees, R., Cardinal, R.N., Price, A., Christmas, D.M., Apergis-Schoute, A.M., Sahakian, B.J. and Robbins, T.W. (2021). Serotonin depletion amplifies distinct human social emotions as a function of individual differences in personality. Translational Psychiatry, [online] 11(1), pp.1–12. doi:https://doi.org/10.1038/s41398-020-00880-9.

Aulinas, A. (2022). Physiology of the Pineal Gland and Melatonin. [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK550972/.

Soares, C.N. and Zitek, B. (2008). Reproductive hormone sensitivity and risk for depression across the female life cycle: A continuum of vulnerability? Journal of Psychiatry & Neuroscience : JPN, [online] 33(4), p.331. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC2440795/.

Wharton, W., E. Gleason, C., Sandra, O., M. Carlsson, C. and Asthana, S. (2012). Neurobiological Underpinnings of the Estrogen - Mood Relationship. Current Psychiatry Reviews, 8(3), pp.247–256. doi:https://doi.org/10.2174/157340012800792957.

Nuffield Health. (2021). Seasonal affective disorder | The signs, symptoms, and treatments. [online] Available at: https://www.nuffieldhealth.com/article/seasonal-affective-disorder-signs-symptoms-treatments.

Greater Manchester Mental Health NHS Foundation Trust. (2023). Behavioural Activation. [online] Greater Manchester Mental Health NHS FT. Available at: https://www.gmmh.nhs.uk/behavioural-activation/.

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This article was written by Riya Verma and edited by Rebecca Pope, with graphics produced by Saba Khan. If you enjoyed this article, be the first to be notified about new posts by signing up to become a WiNUK member (top right of this page)! Interested in writing for WiNUK yourself? Contact us through the blog page and the editors will be in touch.