Smokers are around 70 per cent more likely to suffer from depression and anxiety, a study has revealed.
Researchers said quitting smoking could help people combat the conditions, thereby improving their mental health.
They found that levels of anxiety and depression reported by long-term ex-smokers were indistinguishable from people who have never smoked.
They were also much lower than current smokers.
The study looked at 6,500 people over the age of 40.
It found that 18.3 per cent of smokers reported suffering depression and anxiety, compared with 10 per cent of non-smokers and 11.3 per cent of ex-smokers.
The research, described as the first of its kind to compare the prevalence of anxiety and depression in smokers, non-smokers, and long-term ex-smokers.
The latter group is defined as smokers who have quit for longer than a year.
Experts behind the new study said it dispels the commonly-held perception that lighting up helps relieves stress.
Lead researcher Robert West, professor of health psychology at UCL (University College London), said: ‘Our study found that long-term ex-smokers have similar prevalence of anxiety and depression to non-smokers and considerably lower levels than smokers.
‘Quitting smoking could be the key to improving not only your physical health, but your mental health too.’
The British Heart Foundation (BHF) released the findings ahead of No Smoking Day on March 11.
Associate medical director of the charity, Dr Mike Knapton, said: ‘There is a belief from many smokers that smoking reduces anxiety and stress, which is in turn causing many smokers to put off quitting.
‘Yet, instead of aiding people to relax, smoking increases anxiety and tension.
‘When smokers light up, the feeling of reduced stress or relaxation is temporary and is soon replaced by withdrawal symptoms and cravings.
‘While smoking temporarily reduces these cravings and feelings of withdrawal – which are similar to feeling anxious or stressed – it does not reduce or treat the underlying causes of stress.’
Nearly one in five UK adults smoke, according to the BHF.
SMOKING INCREASES SUICIDE RISK
Smokers are more likely to commit suicide than those who never take up the habit – and the chemicals in cigarettes may be to blame.
Previous research has indicated that smokers are more likely to take their own lives – but it was thought this was because people with psychiatric disorders also tend to smoke.
Researchers from Washington University, St. Louis, suggested the nicotine in tobacco could trigger psychiatric disorders – or make them more severe.
Research published last year found that quitting smoking can be just as effective in tackling depression and anxiety as taking antidepressants.
In fact, the effect of quitting was the same, if not bigger, than for the tablets.
The team, from the universities of Birmingham, Oxford, and King’s College London, analysed 26 studies for their research.
Writing online in the British Medical Journal (BMJ), they said they found people who quit smoking experienced a significant drop in anxiety, depression and stress.
The effect was the same among the general population of smokers as those with a diagnosed mental health problem.
The researchers said: ‘Both psychological quality of life and positive affect significantly increased between baseline and follow-up in quitters compared with continuing smokers.
‘Smoking cessation is associated with reduced depression, anxiety, and stress and improved positive mood and quality of life compared with continuing to smoke.’