What is Seasonal Affective Disorder (SAD)

Seasonal affective disorder or SAD for short is a type of depression that comes and goes seasonally.
The darker, shorter days of the year, with less sun are responsible for a part of the brain (called the hypothalamus) not working properly.

Historically we only ever worked outdoors; two hundred years ago 75% of the population worked outdoors now less than 10% of the population work in natural outdoor light. Whilst this is fine in the Summer months when there are longer daylight hours, in the Winter months, people tend to go to work in the dark and go home in the dark and don’t get to enough natural daylight.

This modern way of living has dramatically altered nature’s cues. A modern day no longer starts at the break of dawn and ends at sunset. Workdays are getting longer and many people face shift work schedules. Additionally, the advent of electric lighting allows social gatherings and personal activities to extend well into the night. These factors have diminished the body’s natural ability to regulate the body clock and this work/life change has resulted in a dramatic increase in light deficiency symptoms.

In the UK and Ireland we are more susceptible to SAD as we are situated in the higher latitudes of the northern hemisphere. As a result, we experience large changes in light levels between the summer and winter. We also experience periods of dark, gloomy weather which can reduce the amount of light we receive and therefore have a profound effect on our body clocks.

A combination of a change in seasonal light, our hectic lifestyles and the periods of darker days and poorer weather, can result in dramatic effects on our circadian rhythms. As a direct consequence of these environmental and lifestyle factors more people than ever before are suffering from Seasonal Affective Disorder.

Does daylight impact your health?

Like many mammals in the natural world, the human body responds to light. As a result our bodies are tuned in to the daylight hours in order to maintain our circadian rhythms. These rhythms regulate many important bodily functions and if you do not receive the correct daylight signals at the correct time this can have significant affects on your wellbeing. Circadian Rhythms help to regulate and control; food digestion, appetite for food, energy levels, sleep quality and length, and mood. Your Circadian Rhythm are effectively your body’s internal clock and if these rhythms are disrupted it can result in you suffering from Seasonal Affective Disorder and may require light therapy

In the distant past human’s lived in the outdoors and were exposed to sufficient levels of sunlight the whole year round even in the northern and southern hemispheres. However, nowadays our lives are mainly carried out indoors due to work pressures, busy lifestyles and change in social behaviours. With the advent of television and now the growth in computer, phone and tablet based entertainment we spend more time than ever indoors and miss out on the light cues our body needs.

Without sufficient levels of morning light our bodies circadian rhythms are not triggered and our body fails to produce the hormones required to feel wide awake. During the day if we do not receive enough sunlight we feel sluggish, lethargic and low in energy and at night we stay awake long after darkness which can result in lack of sleep, disrupted sleep patterns and mood swings. In summary if we do not receive sunlight at the correct times and in sufficient quantities we can upset our body clock to such a degree that the symptoms of SAD ensue.

As a result you need to combat these problems by changing your lifestyle as much as possible, provide your body with daylight at the right times or alternatively use artificial sunlight at the correct times using a medically certified SAD Lamp/Sun Lamp.

There are a diverse range of symptoms of Seasonal Affective Disorder; many are associated with a feeling of general depression – which is why it is sometimes known as the ‘Winter blues’. Below is a list of possible symptoms.

Seasonal Affective Disorder – How do i know if I’ve got it?

An example of SAD Symptoms include:

  • Lethargy, lacking in energy, unable to carry out a normal routine

  • Sleep problems, finding it hard to stay awake during the day, but having disturbed nights

  • Loss of libido, not interested in physical contact

  • Anxiety, inability to cope

  • Social problems, irritability, not wanting to see people

  • Depression, feelings of gloom and despondency for no apparent reason

  • Craving for carbohydrates and sweet foods, leading to weight gain

It is always important to consult your doctor if you believe you have SAD as it may be another condition.

SAD.org.uk provides general information only and should not be regarded as a substitute for medical advice from your own doctor or healthcare provider.
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