Seasonal Affective Disorder (SAD)
For thousands of years,
people have noticed that the seasons can affect our mood. It was
not until the 1980s, however, that the term Seasonal Affective
Disorder (SAD) appeared. It is used for people who, although they
sometimes become depressed in the summer, regularly become
depressed in autumn and winter.
SAD has a lot in common with
other types of depression. It would probably be helpful to read our
general leaflet on Depression before reading
this leaflet about SAD.
What is seasonal affective
SAD is a type of depression
with a particular pattern - it starts in the autumn or winter and
stops in the spring and summer, regularly each year. For this
reason it is sometimes called “recurrent winter depression”.
Many of the symptoms of SAD
are the same as those of 'ordinary' (non-seasonal) depression
(as described in more detail in the Depression leaflet).
These symptoms include:
- low mood (often worse in
- lack of energy
- less “get up and go”
- less interest in life
- being unable to enjoy
- seeing other people
- less interest in sex.
But the symptoms of SAD
are slightly different. In non-seasonal
depression, people commonly sleep less and eat less. In SAD, they
usually sleep more and eat
If you have SAD, you
may find it very difficult to wake up on a winter's morning and can
often feel sleepy during the day. You may crave chocolate and
high carbohydrate foods, such as white bread or sugary foods. If
you have SAD, you probably won't be doing as much physically, so
it's easy to put on weight during the winter.
SAD-type depression recovers
in the spring.Indeed, around a third of people with SAD become
mildly high in mood (hypomanic, as described in the leaflet
Disorder) during the spring and summer.
Who is affected by
Like other types of
depression, SAD is most common in women during the years when they
can have children. It is about three times more common in
women than it is in men. SAD does occur in children and in
older adults, but this is fairly rare.
It is not common in people
who live near the equator – the further away from the equator you
live, the greater the risk of having SAD.
How common is
Many of us will be mildly
affected by the winter with symptoms of feeling slightly
tired, sleeping a bit more and perhaps gaining some weight.
It is a bit like hibernation in animals. If your symptoms are bad
enough to interfere with your life, you may well have SAD. In
the UK, about 3 people in every 100 have significant winter
It seems to be a simple lack
of daylight in winter. We now live much more of our lives
indoors and so see less sunlight. It is thought that a lack of such
light affects how serotonin works in the brain and that this can
make us more likely to become depressed.
Other effects of
Some symptoms of SAD can
create extra problems which make you feel even worse – 'vicious
- If you feel tired all the time, you will probably do less – and
lack of exercise can make depression worse.
- If you are eating more, you may put on too much weight.
- Sleepiness, lack of motivation and irritability can all cause
problems at home, socially, and at work. You don't get round to
doing things that need to be done, and this can add stress to your
Some of the self-help
measures mentioned below can help to prevent these 'vicious
circles' from becoming too big a problem.
These self-help measures
will usually be enough to help mild degrees of SAD, but should
also be used even with more severe SAD.
- Go outside as much as possible during the darker months so you
can see more daylight.
- Carry on any regular exercise you do - best outside since this
gives you daylight as well.
- Tell your family and friends so that they can understand what
is happening and be more supportive.
- Remind yourself that after Christmas the days will be getting
longer and spring is on the way.
This is done with a
lightbox, to try to make up for the shortage of
daylight in winter. The light given out is like sunlight, but
without the ultraviolet rays so it is not harmful to the skin or
From the time that symptoms
start in autumn, you should use a lightbox for 30 minutes to an
hour each day. It is most helpful if you use it at breakfast
time. Light therapy works quite quickly. If it is going to
help, most people will notice some improvement in the first
side-effects are usually mild. You may notice you have
a headache, nausea or blurred vision. These can be
reduced by just moving further away from the lightbox – but not too
far. The further your eyes are away from the light, the less bright
it becomes, so you may need to use it for longer to get the same
effect. It is usually best not to use a lightbox after 5.00
pm because you may then find it hard to get to sleep.
alarm clocks are also used. These come on dimly
about an hour before waking up time and gradually get
brighter. They can be particularly helpful if you find it hard
to wake up on winter mornings.
- desk lights for people with desk jobs
- light visors: these are shaped like a baseball cap with small
lights shining into the eyes.
generally helpful in SAD. Any medication which would make
people more tired or sleepy should be avoided, and so SSRI
antidepressants are usually used (more details in leaflet on
The best evidence is for the use of sertraline, citalopram or
fluoxetine. In SAD, it is usual to start antidepressants in
the autumn and stop them in the spring.
Cognitive behavioural therapy
There is some evidence that
CBT may be helpful to treat winter depression and to prevent it
coming back in future winters. For more
details, see our leaflet describing CBT.
What is the best
For mild symptoms, the
self-help measures described in this leaflet will usually
be enough to help.
For more severe symptoms,
the first choice will usually be between a lightbox and
antidepressants. The choice will often depend on what is
available, what is convenient and what each person prefers.
Only a few studies have
compared light therapy and antidepressants, but it seems that both
treatments work equally well. When one treatment is not enough,
light therapy and antidepressants can be used together.
- Seasonal Affective
Disorders Association (SADA) at PO Box 989, Steyning,
- Winter Blues, Revised Edition: Everything you need to
know to beat Seasonal Affective Disorder by Norman E. Rosenthal,
Guilford Press, New York, 2006 is an excellent source of further
Suppliers of lightboxes and related
- Lumie, 3
The Links, Trafalgar Way, Bar Hill, Cambridge, CB23 8UD
UK, 49 Dalsetter Avenue, Glasgow, G15 8TE
These companies will supply
lightboxes for 3 to 4 weeks on a trial (sale or return) basis.
Anonymous (2009) Management of seasonal affective disorder.
Drugs and Therapeutic Bulletin, 47, 128-132.
Golden, BN et al (2005) The efficacy of light
therapy in the treatment of mood disorders: a review and
meta-analysis of the evidence. American Journal of
Psychiatry, 162, 656-662.
Eagles, JM (2009) Light therapy and seasonal
affective disorder. Psychiatry, 8, 125-129.
Produced by the Royal
College of Psychiatrists' Public Education Editorial Board.
Series editor: Dr Philip Timms
Main author: Professor John Eagles
Service user/carer input: Depression Alliance
Illustration: Lo Cole: www.locole.co.uk
This leaflet reflects the best available evidence available at
the time of writing.
© May 2010. Review date: May 2012.
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