Seasonal affective disorder (SAD) is a well-recognised condition in humans that occurs during the winter period when the shorter days and lack of natural light causes depression-like symptoms because light has a direct effect on hormone production in the body. The reduced light in winter allows greater production of melatonin which can affect sleep cycles and cause symptoms of lethargy and sleepiness. A second hormone, serotonin is also affected by light levels and less is produced in the winter than summer. Serotonin can influence appetite, mood, and sleep, and low levels can drive depressive moods and cravings.
It is now suspected that dogs can be affected by SAD too. A study by the PDSA (the UK’s leading veterinary charity in 2009 found that in the winter dogs were sleepy, grumpier and hungrier, had lower energy levels and didn’t want to exercise. It’s also thought that some cases of hair loss in dogs can be related to hormonal imbalance due to lack of sunlight and sunlight exposure treatments are being prescribed for some sufferers.
However there are some treatments that can help canine SAD sufferers so check with your vet if you think your dog might have the condition. Veterinary medication can help with imbalanced hormones and light boxes will provide artificial sunlight but simple tactics at home like planning long lunchtime walks in the winter rather than early morning or evening, using full spectrum white light bulbs (available from lighting specialists and some retailers) to light your home and feeding a satisfying diet to prevent hunger can all help to hold off the symptoms of SAD in your dog over winter.