Quitline chief executive Paula Snowden said many smokers perceived the habit as a form of stress relief.
"Financial worry, family issues, bereavement and health concerns" were identified by study participants as being key causes of stress.
Being around alcohol and people who were smoking were other common causes of relapse, the research found.
Figures from Quitline show 24.2 per cent of clients had stayed clean at the six-month point last year, up from 20.9 per cent in 2007.
Those who access multiple-services were more likely to succeed, with the quit rate for clients using both internet and phone Quitline services standing at 30.6 per cent. The "phone-only" quit rate was 21.1 per cent, compared to 25.7 per cent for "online-only".
Ms Snowden encouraged all smokers who had previously tried to quit, but relapsed, to get in contact with Quitline today.
"It's really normal to take several attempts to quit smoking and it is important that people don't feel like they have failed.
"I personally took four serious attempts before I quit for good."
The findings also indicated those who had fallen back into their old smoking habit had failed to contact Quitline when their cravings were strong.
"It's hard to reach out when you're feeling vulnerable, but a Quitline adviser can suggest things to do in the tough times."
