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Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD)

SAD is a type of winter depression that affects an estimated 24% of the UK population every winter between September and April, in particular during December, January and February.

It is caused by a biochemical imbalance that occurs due to the shortening of daylight hours and the lack of sunlight in winter.

SAD can range from mild case of the ‘winter blues’ to a seriously disabling illness, preventing sufferers them from functioning normally.


The symptoms of SAD usually recur regularly each winter, starting between September and November and continuing until March or April.

A diagnosis is made after three or more consecutive winters of symptoms, which may include the following

  • Depression
  • Sleep Problems 
  • Lethargy
  • Craving for carbohydrates and sweet foods 
  • Difficulty with concentration and memory 
  • Irritability 
  • Anxiety
  • Tension 
  • Stress is harder to deal with 
  • Loss of Libido
  • Sudden Mood Changes in Spring

Contributory Factors

In people who suffer from SAD, the short daylight hours of winter seem to play havoc with their body’s clock, upsetting their circadian rhythms. There are a number of theories to explain this disruption.

Melatonin – Melatonin is the sleep hormone. Its production is stimulated by a lack of daylight so levels are highest between dusk and dawn. It is thought that SAD stems from an overproduction of melatonin during the long winter nights, leaving sufferers feeling sleepy and lethargic. If your predominate symptoms are tiredness, low libido and lethargy then light therapy has been shown to be very effective when excess melatonin is a factor. You might like to consider having a Comprehensive Adrenal Stress Test which along with measuring the levels of your stress hormones will also measure melatonin as well. Comprehensive Adrenal Stress Test. 

Serotonin – Serotonin is one of our main happy hormones, but production can wane in the winter. Deficiency is known to cause depression, as well as a craving for carbohydrates, another symptom of SAD. Serotonin is made from the amino acid tryptophan so it is essential that a good supply is present in the diet to optimise production. A deficiency of tryptophan or a lack of one of the nutrients needed to help turn it into serotonin can compromise production. A Consultation will help to highlight if this is a problem for you and will be able to give you practical tips to help maximise tryptophan in the diet and also the nutrients that are needed to convert it into serotonin. Book a Consultation.

Imbalanced blood sugar – A diet high in sugars and refined foods can make us feel great one minute and really low the next. This can exacerbate irritability, craving for carbohydrates and sweet foods and difficulty concentrating. Working with Smart Nutrition to learn how to properly balance you blood sugar levels is a great way to help to control SAD symptoms. Book a Consultation.