Dwindling sunlight and wintry weather may leave some of us feeling a little less positive and uplifted than we would like.  This shift in mood is common, but for some individuals a real sense of depression can occur in the autumn and winter months.  In such cases Seasonal Affective Disorder, or SAD as it is commonly known, may be diagnosed. 

People with SAD frequently suffer sleep disruption, carbohydrate cravings and weight gain, depression, irritability, loss of libido, lethargy, joint pain, stomach problems and often find that their ability to cope seems to be lowered.  Treatment aims to lift mood and relieve depression.  You will be pleased to hear that there are some simple steps that can be taken to help.

Last week I mentioned The Sunlight Campaign being run by the National Osteoporosis Society which aims to highlight the importance of getting out in the sunlight in order for the body to manufacture vitamin D which is crucial for bone health (and many other health parameters!).  Today I wanted to look at the link between sunlight and mood.

The changing seasons can affect our mood and behaviour, this is a natural process that can clearly been seen in animals – and we are no exception.  Many of us will find that we want to eat a little more and sleep a little more in the winter and that the dark mornings and short days are not to our liking.  For some people these kinds of symptoms are severe enough to disrupt normal daily life and cause real distress.  These individuals are said to suffer from SAD.  SAD is characterised by episodes of depression in autumn/winter and is thought to be caused because of lack of daylight.  Our bodies have an internal 24hour clock or cycle, known as the circadian rhythm.  This cycle of day-night is affected when the daylight hours shorten in autumn/winter.  Sunlight is known to affect certain mood chemicals in the brain such as serotonin and melatonin, if there is less light then less serotonin is produced and this may lead to low mood.

Light therapy
Bright light appears to immediately have an effect on mood via the brain chemical serotonin and the pathways involved in its production (1,2,3).  There have been many studies (too many to list), which show the beneficial effects of light therapy for those suffering with SAD.  Light boxes are available to buy online and in stores and do make a real difference.  Make sure that you follow the manufacturers instructions and if you are also seeing a doctor work with them in order to gain maximum benefit.  Most people find that morning use of the light box, for between 30 minutes to an hour, is most helpful.  The light emitted from these units has a similar spectrum to daylight (it is thought hat the light needs to be at least 2,500 lux in order to be beneficial).  Daylight bulbs are also available to buy.

Bright light may actually help us all in the winter.  A study carried out in the year 2000 (4) found that bright light improved vitality and mood among people with SAD but also in healthy subjects with no SAD but who worked indoors during the winter.  This does not surprise me, if you work indoors during the winter months you are more than likely to arrive at work while it is dark, sit in the office in false light and leave when it is dark outside thus never seeing natural daylight.  Getting out for a lunchtime walk or buying a small daylight lamp unit to sit on your desk at work may make a real impact on your mood.

Dawn simulation
Some studies (5,6,7)  have now been carried out with dawn simulators for SAD.  These simulators (daylight alarm clock) are now widely available to buy and usually consist of a unit with a light that gradually increases in intensity over a 30 minute period until it is at it’s brightest when an alarm usually sounds.  The thinking behind the sunrise alarm clock is that in the winter we often wake up with a start when the alarm goes off, but it is still very dark outside.  Our bodies awake with a shock and then we turn on a bright light, we miss the normal cues to the body that occur with dawn and increasing light.  If we wake up with gradual, dawn light our circadian rhythm / natural body clock, is less disrupted.  The studies have proved very positive with some indication that the dawn simulation sunrise alarm clocks, are as good as light boxes at helping mood in SAD sufferers.

Check back later in the week for more information on SAD.

You may also wish to contact the the 'Seasonal Affective Disorder Association' a registered charity which informs the public and health professions about SAD and supports and advises sufferers of the illness.

(1)Grass F & Kasper S.  2008.  Humoral phototransduction: light transportation in the blood, and possible biological effects.  Med Hypotheses.  71:314-317
(2)Aan het Rot M et al.  2008.  Bright light exposure during acute tryptophan depletion prevents a lowering of mood in midly seasonal women.  Eur Neuropsychopharmacol.  18:14-23
(3)Hoekstra R et al.  Effect of light therapy on biopterin, neopterin and tryptophan in patients with seasonal affective disorder.  Psychiatry Res.  120:37-42
(4)Partonen T & Lonnqvist J.  2000.  Bright light improves vitality and alleviates distress in healthy people.  J Affect Disord.  57:55-61
(5)Terman M & Terman JS.  2006.  Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder.  Am J Psychiatry.  163:2126-2133
(6) Avery DH et al.  2001.  Dawn simulation and bright light in the treatment of SAD: a controlled study.  Biol Psychiatry.  50:205-216
(7)Avery DH et al.  1993.  Dawn simulation treatment of winter depression: a controlled studyAm J Psychiatry.  150:113-117

Written by Ani Kowal