Seasonal Affective Disorder (SAD)

Seasonal Affective Disorder (SAD) is a form of depression also known as seasonal depression or winter depression. Symptoms and mood changes of those with SAD are similar to those with depression. The symptoms usually occur during the fall and winter months when there is less sunlight and usually improve with the arrival of spring. Although it is not as common, some people do experience SAD in the summer.

Those with SAD are said to have a biochemical imbalance in the brain prompted by shorter daylight hours and less sunlight in winter. As seasons change, they experience a shift in their biological internal clock that can cause them to be out of step with their daily schedule. SAD is more common for those living far from the equator where the days are much shorter during winter.

Experts said that this disorder rarely applies in Singapore, where there is plenty of sunlight all year round. Mr. Gifford Chan, principal clinical psychologist at Mind Care Therapy Suites, said, "Even our rainy season does not deprive us of sunlight to the extent of SAD."


Signs and Symptoms

Symptoms of SAD can include:

  • Feeling sad or having a depressed mood
  • Loss of interest or pleasure in activities once enjoyed
  • Changes in appetite
  • Change in sleep
  • Loss of energy or increased fatigue
  • Increase in purposeless physical activity
  • Slowed movements or speech
  • Feeling worthless or guilty
  • Difficulty thinking, concentrating, or making decisions
  • Thoughts of death or suicide

For Winter-Patterned SAD, additional specific symptoms may include:

  • Oversleeping
  • Overeating
  • Weight gain
  • Social Withdrawal

Specific symptoms for Summer-Patterned SAD may include:

  • Trouble sleeping
  • Poor appetite
  • Restlessness and agitation
  • Anxiety
  • Episodes of violent behaviour


Risk Factors

SAD sometimes runs in families, and is more common in people who have relatives with other mental illnesses, such as major depression or schizophrenia.

Research indicates that those with SAD may have reduced activity or serotonin, which helps regulate mood. Research also suggests that sunlight indirectly helps maintain normal serotonin levels, but for those with SAD, this regulation does not function properly, resulting in decreased serotonin levels in the winter. Other findings suggest that people with SAD produce too much melatonin - a hormone that is central for maintaining the normal sleep-wake cycle. Overproduction of melatonin can increase sleepiness.



There are four main treatment types which may be used alone or in combination:

✽   Light Therapy

Light therapy involves sitting in front of a light therapy box that emits a very bright light (and filters out harmful ultraviolet (UV) rays).

✽   Psychotherapy

Talk therapy, particularly Cognitive Behavioural Therapy (CBT), can effectively treat SAD. It focuses on replacing negative thoughts related to the winter season (e.g., about the darkness of winter) with more positive thoughts.

✽   Anti-Depressant Medications

Selective Serotonin Reuptake Inhibitors (SSRIs) are the type of anti-depressant most commonly used to treat SAD.

✽   Vitamin D

For some people, increased exposure to sunlight can help improve symptoms of SAD. For example, spending time outside or arranging your home or office so that you are exposed to a window during the day. (Don't forget your sunscreen!)


Learn more about SAD through the video attached.