Anxiety and depression more common among smokers
While as many as one in three smokers think lighting up can relieve stress, new research shows that smokers are actually 70 per cent more likely to say they are anxious or depressed than non-smokers.
Levels were also much lower than current smokers.
"Quitting smoking could be the key to improving not only your physical health, but your mental health too," said University College London's Professor Robert West, the study's lead author.
The study involved 6,471 people over the age of 40 and found that 18 per cent of smokers reported moderate or extreme depression or anxiety, in comparison to 10 per cent of non-smokers, and 11 per cent of ex-smokers.
These results also support a recent review, published in the British Medical Journal, which found that quitting smoking was associated with reduced depression, anxiety and stress, as well as improved positive mood and quality of life.
Dr Claire Knight, Cancer Research UK's health information manager, said smokers had to overcome both physical and mental hurdles to break their tobacco addiction.
"But breaking that addiction and becoming a non-smoker is the best thing smokers can do to improve their health.
"Ahead of No Smoking Day, these findings are a reminder that the NHS Stop Smoking Service is the best way to increase your chances of quitting, and provides accurate information and support to overcome an addiction that kills around 100,000 people in the UK every year," she added.
Professor Dame Sally Davies, Chief Medical Officer said it highlighted that quitting smoking is a "double win - along with all the physical health benefits, smokers' mental health appears to improve as well".
The researchers also suggest that the findings from this study could help influence policy around stop smoking interventions.
"Improvement in mental health should be factored into health economic evaluations of smoking cessation interventions more directly," they write.