Seasonal Affective Disorder: 5 scientific ways to stay happy this winter

It is that time of the year when the days get shorter, the temperature gets cooler, the landscape is coloured red and brown with festivities to look forward to. Autumn also brings about changes in mental state of up to 10% of the population [1].

What is seasonal affective disorder?

As daylight hours shorten, many people experience low moods, lethargy, and sleepiness. This is called seasonal affective disorder (SAD), a seasonal condition which appears during autumn/winter. Those experiencing SAD report recovery from symptoms by spring/summer. Changes in body clock and brain chemicals imbalance are two possible causes of SAD [2].

SAD: what happens in your brain?

Your body clock is in alignment with the day-night cycle. Due to shorter days and late-onset of dawn, less light enters the eyes. Light that enters the eyes regulates the body clock and sleep-wake cycle. This involves the production of brain chemicals that influence mood and mental state. Low light during autumn/winter affects this process.

Brain chemicals that play an important role in SAD include melatonin and serotonin.

Reduction in sunlight promotes higher production of melatonin, the brain chemical that regulates sleep [3]. People produce higher levels of melatonin in winter compared to summer [4], contributing to sleepiness and low energy levels.

Vitamin D, which is activated by sunlight, is needed to produce serotonin, your feel-good brain chemical. Low vitamin D levels affect serotonin production [3]. In addition, during autumn and winter, serotonin’s availability in the brain is reduced. This lowers its ability to perform the function of uplifting your mood [5].

SAD treatments

There are several scientifically proven seasonal affective disorder tips that you can adopt for a happier winter:

1. Light therapy

    The National Health Service (NHS) has recommended light therapy as a SAD treatment [6]. This is a safe and accessible option and requires you to sit near a light source, referred to as a SAD light box or a SAD lamp, for 30 minutes each morning [7]. The intensity of light recommended is 10,000 lux (equivalent to direct sunlight). This therapy helps the brain regulate its body clock and brain chemicals production by providing sufficient light during dark days. Research has shown that 3 weeks of bright light (6000 lux) treatment in the morning led to overcoming depressive symptoms in 61% of participants [10]. Read more about this here.

2. Optimal nutrition

   Good nutrition practices to ensure intake of all essential vitamins and minerals can help manage symptoms. A specific diet with foods for seasonal affective disorder is yet to be evidenced. One notable nutrient is 5-HTP. This is the direct precursor to serotonin. Supplementing with 5-HTP increases serotonin levels in the brain, which will help regulate your mood. Starting at £13.99 , you can read more about this here.                                                          

3. Exercise

   Practising physical activity has consistently shown to improve mental health. 2 studies involving those with SAD found that an hour of morning exercise for 2 weeks reduced depressive symptoms and improved mood by 50% [8][9]. A study employing physical activity (1 hour of stationary bicycle) found that a week of exercise reduced depressive symptoms by almost 70% [10]. The same study treated SAD patients with bright light therapy and found it reduced symptoms by almost 65%

4. CBT

   The National Institute of Health and Care Excellence (NICE) recommends use of cognitive behaviour therapy as one of the treatments for SAD [11]. CBT is a talk therapy which can be delivered in person, through telephone or online by a trained professional. It focuses on physical symptoms, thoughts, feelings, and behaviour. This therapy empowers individuals with stress reduction, problem-solving, coping, and self-management strategies. One protocol states that 90-minute sessions twice a week over six weeks show benefits for SAD symptoms [2]. 6 weeks of CBT was almost 20% more effective than light therapy for long term SAD symptoms resolution [12

5. Combined therapies

   A combination of the above treatments work better due to the synergistic effect. A combination of light therapy and CBT led to SAD recovery in 70% of the participants, compared to 40% of CBT and 50% of light therapy treated participants [13]. Exercising under bright light (2500 lux) led to greater reduction in depressive scores compared to exercising under regular room light [14].

The mood changes brought about by SAD can be easily managed by simple and clinically effective treatments like light therapy, good nutrition, exercise, and cognitive behaviour therapy. 

 References:

1. Meesters, Y. et al. (2016). Seasonal affective disorder, winter type: current insights and treatment options. Psychology research and behavior management, 9, 317–327.
2. Roecklein, K. A. et al. (2005). Seasonal affective disorder: an overview and update. Psychiatry (Edgmont (Pa. : Township)), 2(1), 20–26.
3. Munir S, Abbas M. Seasonal Depressive Disorder. [Updated 2022 Mar 26]. In: StatPearls [Internet].
4. Morera, A. L. et al. (2006). Seasonality of psychopathology and circannual melatonin rhythm. Journal of pineal research, 41(3), 279–283.
5. Campbell, P. D. et al. (2017). Bright Light Therapy: Seasonal Affective Disorder and Beyond. The Einstein journal of biology and medicine : EJBM, 32, E13–E25.
6. NHS (2021). Treatment - Seasonal Affective Disorder (SAD). [online] nhs.uk.
7. Campbell, P. D. et al. (2017). Bright Light Therapy: Seasonal Affective Disorder and Beyond. The Einstein journal of biology and medicine : EJBM, 32, E13–E25
8. Kurz, B. et al. (1995). Early morning exercises (aerobic) reduce depression scores in ‘‘winter-depressed’’women (SAD/S-SAD). Soc Light Treatment Biol Rhythms, Abst, 7, 35.
9. Koehler, W. K. et al. (1993). Feedback loops in the circadian system: Experiences with physical exercise in the treatment of SAD. Biol Rhythm Res, 24: 298–299.
10. Pinchasov, B. B. et al. (2000). Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light. Psychiatry research, 94(1), 29–42.
11. NICE (2022). Overview | Depression in adults: treatment and management | Guidance | NICE. 
12. Rohan, K. J. et al. (2016). Outcomes One and Two Winters Following Cognitive-Behavioral Therapy or Light Therapy for Seasonal Affective Disorder. Am J Psychiatry. 1;173(3):244-51.
13. Rohan, K. J. et al. (2004). Cognitive-behavioral therapy, light therapy, and their combination in treating seasonal affective disorder. J Affect Disord. 80(2-3):273-83.
14. Leppämäki S. et al. (2002). Bright-light exposure combined with physical exercise elevates mood. J Affect Disord. 72(2):139-44.