By Hazel Grassie.
What is Seasonal affective disorder?
The summer months bring us warm, long days leaving us feeling energetic and positive. During the bitter cold winter months, it is normal that we find ourselves eating more, sleeping longer and struggling to get out of bed each morning. This change of seasons has a much more profound affect on people with Seasonal affective disorder (SAD). SAD is described by the NHS as ‘a type of depression that comes and goes in a seasonal pattern’. Symptoms of SAD, including persistently low moods, changes in thoughts, negative feelings and a lack of interest in everyday activities, are generally at their worst in the months of December through February. Alongside the main symptom of depression, SAD patients experience lethargy, sleepiness during the day, difficulty concentrating and increased appetite often leading to weight gain. The severity of symptoms differs greatly between SAD sufferers. Whilst some find SAD only irritating, others are extremely affected in their day-to-day lives.
Diagnosis and prevalence
As the symptoms of SAD overlap with other types of depression, a diagnosis is made on the basis of the occurrence of depression during winter months and its absence otherwise. It often takes a couple of years to establish this pattern. Countries that have a more significant change in weather, temperature and light have greater incidence of SAD compared to countries close to the equator where seasonal variation is less substantial. The prevalence of SAD in northern Europe is thought to be 1 in every 10 people.
It is easy to understand why we might feel a bit down in coping with dark, cold days for 3 months of each year. But what actually causes us to be affected by it?
Our body has a natural biological clock. The ‘master clock’ is located in the SCN region of the brain. The optic nerve relays information to the SCN about light levels detected by our eyes. The SCN interprets these light levels and induces the production and release of the appropriate hormones. For example, if darkness is received the SCN will induce the production of melatonin (our sleep-inducing hormone) to make us sleepy. This biological clock is the driver behind our circadian rhythm, described as ‘physical, mental and behavioral changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in our environment’. Simply put, our circadian rhythm influences hormone release and our sleep pattern. As our circadian rhythms function majorly on sunlight, this system is disrupted during winter months. The most accepted theory for SAD is that the prolonged lack of sunlight stops the hypothalamus of the brain working correctly. As a result, the body produces less serotonin (our happy hormone). As serotonin is the precursor hormone to melatonin, we also have less melatonin leading to disrupted sleep cycles and having to spend longer in bed to compensate for bad sleep patterns.
The carbohydrate-serotonin connection
In addition to giving a feeling of well-being, serotonin also plays a role in regulating hunger as an appetite suppressant. We don’t feel we need to eat so much in summer months as we have higher levels of serotonin induced by sunny days and better health. Another way that serotonin is made and released is after eating sweet or starchy carbohydrates. Tryptophan (a protein from food) is needed to make serotonin in the brain. However, tryptophan struggles to compete for receptors with many other proteins in the blood. When we eat carbohydrates, the presence of glucose in the blood causes insulin to be released. This insulin encourages the uptake of other proteins from blood into active organs, whilst tryptophan stays behind in the blood. Now when it passes the brain it can enter due to decreased competition with other proteins. Put simply, eating carbs enables the uptake of serotonin building blocks at the blood-brain barrier. Our winter cravings for carbohydrates are quite possibly a natural response to the lack of sunlight-derived serotonin, in attempt to better our low moods.
Treatment of SAD
Phototherapy and home environment
Light therapy (phototherapy) is the most common and effective treatment of SAD. Phototherapy employs different types of lamp boxes, visor lights and dawn simulators that emit specialized fluorescent light designed to bring extra light to the eyes. They are to be placed around the house for additional lighting. It would of course be nice to jet off to a tropical destination abroad when winter falls each year, but unfortunately in most cases, this isn’t an option. Instead, simple alterations to the home environment can make a huge difference to mood levels. Taking steps like trimming overgrow hedges to allow sunlight through windows and painting rooms light colours will create a greater sense of space and brightness. It is advised to brave the cold weather and spend some time outdoors when the sun is highest. It is also an idea to see a psychiatrist with experience in treating SAD. In severe cases of SAD, antidepressant drugs are sometimes administered by a GP.
Diet and exercise
Boosting serotonin levels is the aim of the game here. A healthy diet will help you to control wait gain over winter and provide the nutrients needed to feel great inside and out. As discussed, our cravings for carbohydrates in winter are related to the need to increase serotonin levels. However, overeating refined carbs like white rice, pasta and bread will result in sugar spikes and successive lows and often weight gains. The sugar crash afterward may attenuate depression leaving one feeling worse than before. By contrast, carbs that release their sugar slowly into the bloodstream (low GI, complex carbs) like vegetables and unrefined cereals are the best ones to choose for improving moods during the winter. Choose lean meats like chicken and turkey as well as oily fish like salmon to provide your body with the protein (particularly tryptophan) it needs to build hormones, maintain cells and repair damaged tissue.
Include flax seeds and walnuts at breakfast, in smoothies or as a snack to supply your body with omega 3, shown to benefit mood. Folic acid found in leafy greens like spinach and kale is thought to aid in the production of serotonin. Although research on this is inconclusive, it will do not harm to include these foods into your daily diet. Low levels of vitamin B12 are linked to depression. To help swerve winter blues, include B12 sources like lean beef, eggs, wild salmon and yoghurt.
Finally, exercise releases endorphins, which make us feel good and creates a positive feedback loop encouraging us to exercise again. Although it is tempting to stay cozy in the house, it is worth going to an exercise class, swimming or to the gym to keep your spirits high. Group fitness will allow you to socialize at the same time, which is also good for positive vibes. To sum up; for some people the winter season isn’t just a tiresome slog but a real struggle day-to-day that can require GP assistance and medication. However, light therapy, eating wisely and keeping active are all effective measures to really boost inevitably low moods during this season.
Read more about Seasonal Affective Disorder from the following links: