Why it's good to smile
There's nothing quite like a winsome smile for perking you up, as well as those around you.
Smiling, laughing, and positive thinking have been shown to have a huge number of health benefits to both mind and body.
Stress has been linked to a number of health problems, including heart disease, Type 2 diabetes, high blood pressure and obesity.
When you laugh, your body releases endorphins. These are brain chemicals known as neurotransmitters, which make us feel happy. They are also a natural pain and stress reliever.
Laughing reduces levels of cortisol, the stress hormone, and gives us a quick burst of energy.
A good laugh can be beneficial to the lungs, boost immunity, and could even burn off calories.
Smiley, happy people are thought to have more friends and be more successful, by appearing more confident and approachable.
The science behind a smile
Medical reason for not smiling
A small number of people suffer from Moebius Syndrome, which means that they are physically unable to smile.
The condition affects the nerves that help us smile, frown, blink and perform other facial expressions.
You may think that people smile because they are happy, but scientific research suggests otherwise.
'Simply using the same muscles as smiling will put you in a happier mood,' explains Dr Michael Lewis, psychologist at Cardiff University.
'That's because use of those muscles is part of how the brain evaluates mood.'
Charles Darwin was one of the first to suggest our expressions may actually intensify our feelings. This theory is known as the 'feedback loop' or 'facial feedback hypothesis'.
A smiling expression feeds back into how we experience mood, therefore making us feel happier or a joke seem funnier.
Professor Fritz Strack, along with Leonard L Martin and Sabine Stepper, investigated this theory and published a study in 1988.
This revealed that people who used their smiling muscles when presented with cartoons found them more amusing than people who didn't.
Separate studies have shown that people suffering from facial paralysis, and without the ability to smile, have been found to suffer more from depression.
Can smiling relieve stress?
Did you know?
A genuine smile is known as a 'Duchenne smile' after the French physician Guillanne Duchenn.
This involves smiling with the mouth and crinkling around the corners of your eyes.
A polite functional smile is known as a 'Pan American smile', and involves stretching the mouth, but doesn't use the eyes.
Mark Stibich, PhD, a consultant at Columbia University, and contributor to a Guide to Longevity at about.com, believes smiling may also act as a stress relief.
'When you're stressed a number of things happen to your body,' explains Stibich.
'Your pulse rate shoots up, your digestive system shuts down, and your blood sugar levels increase.
"But two things also happen that you have voluntary control over – your breathing becomes shallower and faster and facial expressions kick in.
'If you can slow your breathing down and change your expression, you may be able to turn around the stress cascade.'
How to put a smile on your face
Spend time with friends and family who are most likely to cheer you up.
Take time out and watch a film or a TV show you find funny.
Even when you don't feel like it, try and force yourself to smile – you may find that a forced smile becomes genuine.
Reflect on happy memories by looking through photographs.
Need more help?
A perfect smile
Don't let the condition of your teeth put you off from smiling. Make sure you brush them twice a day with a fluoride toothpaste.
It's also a good idea to visit your dentist regularly and to cut down on sugary foods and drinks.
If you're feeling low or depressed, there are lots of people who can help you, especially if you'd prefer to speak to someone impartial.