With the unforgiving, dreary grey skies and darker days and nights, it's easy to find ourselves longing for summer, or the feeling of sun on our skin.

Yet, while these winter days can leave many of us feeling deflated or lower in energy, for some that winter funk is harder to shake. In fact, the feeling of sadness during the cooler months can be crippling for millions of people. So much so that depression during the Autumn and Winter months is a common condition, known as Seasonal Affective Disorder, or SAD.

SAD is a form of depression that is triggered by a lack of daylight hours and sunlight. Astonishingly, at least one in five of us suffers from mild SAD (two million people in the UK), while 2 per cent are so severely hit that their every day lives are affected.

Why Does It Happen?

It's thought that a lack of sunlight and vitamin D (the so-called sunshine vitamin) can wreak havoc on our brain's chemicals and hormones, as well as our internal body clocks, triggering feelings of depression as a result. A lack of sun can also affect our Serotonin levels, which can lead to mood swings and changes.

How Can SAD Affect Me?

SAD, like depression, comes with lots of symptoms and can affect each and every one of us in different ways. However, here are some of the symptoms, although it is worth remembering that you don't need to check every single one for a diagnosis. If you are worried you may be suffering, always consult with your GP and chat things through.

• Major Depression: You may suffer with low moods or feelings of worthlessness and guilt. You could even experience a lack of interest in activities you previously loved, or you may feel drained, have difficulty concentrating, or thoughts of self-harm.
• Anxiety or agitation
• Oversleeping or insomnia
• Changes in appetite or weight gain
• Loss of interest in sex
• Irritability
• Low energy

How Can I Help?

First of all, have a chat with your GP if you think you have SAD. While most of us can't afford to leap on a plane for a sun-filled holiday, they may advise you to try counselling or even light therapy, which can help in a massive 85 per cent of cases.

You could also invest in a special box which mimics outdoor light. Other simple ways to spread some joy include exercising (if you can bear to exercise outdoors to boost your vitamin D levels, lace up your trainers and go!) to send endorphins soaring, taking a vitamin D supplement (we recommend oral sprays, if you can find them), spending more time outdoors and eating quality dark chocolate - our favourite food is a known mood booster as it can raise dopamine levels in the brain.

Advice and Support:

If you think you may be suffering with SAD, then please know that you are not alone - what you are feeling is normal! You should also chat things through with your GP as soon as possible. You can also find help and support at the Seasonal Affective Disorder website by visiting www.sada.org.uk