SAD, which stands for Seasonal Affective Disorder, isn’t just a case of the winter blues. It is a form of major depression and can be seriously debilitating, causing symptoms such as chronic low mood, excessive sleeping, carbohydrate cravings, irritability, poor concentration, low libido and lethargy. SAD occurs most typically throughout the winter months and currently affects around 6% of the UK population, and between 2-8% of people in other countries of higher latitude such as Sweden, Canada and Denmark. 

Curiously, around 80% of sufferers are women, mostly those in their early adulthood. Scientists such as Dr Robert Levitan, professor at the University of Toronto, have speculated that this may be due to evolutionary purposes, which encourages women of reproductive age to slow down during the winter months to help preserve energy, leading to healthier pregnancies. 

Research has yet to come to a definitive conclusion as to what causes SAD, however, there are a number of underlying biochemical triggers that have been identified. 

A leading theory looks at serotonin production and how levels of this neurotransmitter in the body are significantly affected by the amount of available sunshine. Research shows that exposure to sunshine has an impact on the binding-capacity of serotonin to receptor sites in the brain, which essentially allows serotonin to work its magic, leading to feelings of contentment and happiness. 

Other research also indicates how those suffering with SAD tend to have a dysregulated production of melatonin, the hormone produced in the pineal gland in response to darkness, which induces sleep. Instead of being produced in the evening, helping the body settle for the night, studies in those that suffer with SAD show melatonin being secreted during the day, hence feeling the need to sleep all the time and lack of energy. 

There are a few other biochemical underpinnings in the pathogenesis of SAD, however, there are some key nutrition and lifestyle strategies based on these initial findings, which can help support mood throughout the winter months.  

1. Get your body clock in check 

Our body’s hormones and biological processes are majorly governed by a natural, internal circadian rhythm, which regulates our sleep-wake cycle and is programmed by daylight and night. A disrupted circadian rhythm can be caused by shift work, not enough exposure to daylight, stress, insomnia and too much exposure to blue light in the evening, which can lead to an imbalance in neurotransmitters such as serotonin and melatonin. 

This is why it is incredibly important to try and attune the body to these cycles as much as possible, by doing things like avoiding electronic screens at night and doing relaxing activities to encourage melatonin production, as well as exposing the face to daylight first thing in the morning, or if it’s dark, buying a light therapy lamp. Putting these strategies into place, can help the body recalibrate and realign to a healthy sleep-wake cycle. 

2. Check your vitamin D levels

Research shows that having sub-optimal levels of vitamin D3 can interfere with proper serotonin production. Whilst scientists don’t understand exactly how, there is a significant body of research that demonstrates a strong link between vitamin D3 levels and depression.In one particular study, scientists found that vitamin D3 helps to convert the amino acid, tryptophan, into serotonin. 

Check your vitamin D3 levels and make sure that they are above 75 nmol/L, for optimal serotonin production. 

3. Balance your blood sugar levels 

More than any other organ in the body, the brain is dependent on a constant supply of energy, which very much related to our diet. Eating foods that are high in sugar and simple carbohydrates leads to rapid fluctuations in blood sugar levels, which can have a significant impact on the brain and its neurotransmitters. Typical symptoms of imbalanced blood sugar levels are low mood, anxiety, brain fog and fatigue. 

This is why it is important to eat foods that provide the body and brain with a consistent and sustainable source of energy. This means making sure you’re eating complex carbohydrates that contain ample amounts of fibre, such as brown rice, starchy vegetables and tubers like sweet potato, butternut squash and beets, as well as eating protein-rich foods with every meal and snack. Avoiding refined grains like white bread, pastries, cakes, biscuits and white rice, as well as foods with added sugar like in processed foods, sweet yoghurts, fruit juices and cereals, is absolutely key to avoiding blood sugar imbalances. 
4. Get moving! 

According to a recent study published by JAMA Psychiatry, people are 26% less likely to become depressed with regular physical activity. It is well established that exercise can stimulate the release of endorphins such as serotonin, dopamine and norepinephrine – all of which regulate mood and prevent symptoms of depression. 

We also know that exercise stimulates the release of protective molecules such as Brain-Derived Neurotrophic Factor, which helps to trigger the growth of new brain cells. 

The key takeaway is to include some form of movement into your everyday life to help encourage the brain to produce its ‘feel-good chemicals’. Whether it’s fast paced walking or a more intensive exercise like HIIT, it is vital to be moving.