How can Nutrition support Seasonal Affective Disorder (SAD)?


Now that winter is here, our days are drawing to a close earlier and many of us just want to curl up on the sofa with a cup of tea, biscuits and a Netflix series!


The outdoors becomes increasingly unappealing with its grey skies and cold, damp weather. Our energy takes a significant dip which accompanies a desire to sleep more and comfort eat, usually something sugary and sweet!


However, our lower mood in the winter may be due to more than just the chilly temperatures outside. Within this blog we will discover how Nutrition can support SAD, what is happening in the body and learn what we can do to help ourselves feel more positive about the winter months ahead.



What is Seasonal Affective Disorder (SAD)?

SAD is also known as ‘the winter blues’ and is a type of depression. According to the NHS, ‘the exact cause of SAD is not fully understood, although may be that a lack of sunlight might cause a shift in how the hypothalamus works’, which is a part of the brain that controls several important functions including sleep and growth. SAD is most common in those between ages 18-30 and is now affecting many more of us.


Although it can affect individuals at any time of year, SAD mainly affects us in the winter; when darkness looms earlier and our daylight hours get shorter. It can cause significant changes in our mood. For many of us, it can affect our daily routines causing feelings of despair, anxiousness, lethargy and finding it difficult to wake up. It can also cause us to crave carbohydrates to feel better and there is a tendency for people to comfort eat in the winter time.


There are many factors that can cause depression - for some people it develops without a specific reason. While feeling sad from time to time is completely normal, if you feel sad for prolonged periods or at the same time each year, it may be a sign of SAD. The symptoms are similar to those of normal depression, but they occur repetitively at a particular time of year.


Signs of SAD include:

  • a persistent low mood

  • a loss of pleasure or interest in normal everyday activities

  • feeling irritable

  • feelings of despair, guilt and worthlessness

  • low self-esteem

  • tearfulness

  • feeling stressed or anxious

  • a reduced sex drive

  • becoming less sociable

  • changes in how much you eat

(1).


In SAD, what is happening in the body?


Serotonin, also known as the ‘happy hormone’, affects our sleep, mood and appetite. Sunlight creates higher levels of serotonin in our bodies, so when there is a lack of sunlight in the winter months we have much lower levels of this hormone, which is linked to depression and low moods (2).


Melatonin is also known as the ‘sleep hormone.’ People with SAD may have difficulty with an overproduction of melatonin. As the winter days become darker, melatonin production increases and, in response, those with SAD feel sleepy and lethargic (3).


Your body’s internal clock is also known as Circadian Rhythm which uses sunlight to time important functions. When this is disrupted, due to the decrease in sunlight, it may disrupt your body's internal clock and lead to feelings of depression and SAD (4).


Other factors causing SAD can be stress or a genetic predisposition. Those who have lived near the equator and then moved further away are also more likely to develop symptoms. In northern Europe an estimated 1 in 10 suffers with SAD, and the condition is ‘extremely rare’ in countries near the equator where daylight hours are long (5).



What can you do to tackle SAD symptoms?


Self Care - Getting as much natural sunlight as possible in the morning is so important; and even just a short morning walk before breakfast can make the world of difference to your mood for the rest of the day. When light hits the back of your eye, messages go to the part of your brain that controls sleep, appetite, sex drive, temperature, mood and activity. If there isn't enough light, these functions can slow down and gradually stop (6). Some are more susceptible to SAD than others, meaning they need more daylight to function.

Try to sit by a window, spend time in parks or gardens in the natural light. Also making some meals in advance will be so helpful if you lack the energy to cook in the evening. This way you will have a healthy home cooked meal to eat, providing your body with the vitamins and minerals you need to feel your best.



Vitamin D - Low levels of vitamin D, caused by low dietary intake of the vitamin or not enough exposure to sunshine have been found in people with SAD (7). Vitamin D is found in oily fish (tuna, mackerel, salmon), cheese, egg yolks, and some fortified foods like orange juice, dairy products, soy milk and cereals. Although in the winter it is important to supplement this vitamin, as the main way vitamin D absorbs is through our skin from sunlight.

Vitamin D Tip - Make sure to choose a supplement with the D3 form (cholecalciferol) as this is the form that is naturally produced in the skin in response to sunlight (8).


Protein & Healthy Fats - When our mood is low, its natural to crave carbohydrates and sugary foods, especially in the winter time. Instead focus on consuming more protein, which is what makes your 'feel good’ neurotransmitters, serotonin and dopamine (9). Eat plenty of oily fish, high quality protein like lean meat, fish, nuts, seeds, beans, chickpeas and lentils.


Omega 3s - EPA and DHA are omega 3 fatty acids found in oily fish, and they are incredibly important for overall brain function and development. EPA and DHA have been studied extensively for their benefits (10). Sardines, anchovies, mackerel, salmon and herring are known to have lower levels of mercury and are rich in these omega 3 fatty acids. Oily fish also contain vitamin D so you are getting this added benefit too! Vegetarians and vegans who avoid fish can take an algae supplement which also contains EPA and DHA.


Magnesium - Magnesium is a mineral which is often depleted in individuals, mainly due to not getting enough through out diets. This powerful mineral contributes significantly to our mood and energy, and can be found in dark leafy greens, nuts, seeds, whole grains (11).


Tryptophan/Serotonin - The ‘happy hormone’ serotonin, is made in the body by the amino acid Tryptophan. Make sure to eat foods rich in this amino acid; such as dairy, oats, tofu, turkey, chicken, salmon, tuna, edamame beans, squash and pumpkin seeds, eggs and peanut butter (12).


Light Therapy - Some find it helpful to use a light box, lamp or alarm clock, which gives off a very bright light that mimics sunlight. Light therapy has been researched to put you in a better mood, boost energy and help you to feel more alert. This is now widely used and is an extensively investigated treatment for SAD (13).



REFERENCES


  1. https://www.nhs.uk/mental-health/conditions/seasonal-affective-disorder-sad/symptoms/

  2. https://pubmed.ncbi.nlm.nih.gov/23329523/

  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673349/

  4. https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651

  5. https://www.mind.org.uk/information-support/types-of-mental-health-problems/seasonal-affective-disorder-sad/about-sad/

  6. https://www.mind.org.uk/information-support/types-of-mental-health-problems/seasonal-affective-disorder-sad/causes/

  7. https://www.nccih.nih.gov/health/seasonal-affective-disorder

  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/

  9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7025515/

  10. https://pubmed.ncbi.nlm.nih.gov/22332096/

  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316205/

  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728667/

  13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6746555/

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