Increasing the risk of heart disease, cancer, respiratory diseases, pregnancy complications - the dangers of smoking are already well established. However, now scientists have discovered that smoking may also affect sleep.

According to a team from Florida in the US, sleep disturbances resulting in insufficient sleep have been linked to poor physical and mental heath outcomes. However, little research has been carried out on the possible links between smoking and poor sleep.

The scientists decided to investigate this further. They studied sleep disturbances in almost 5,000 people over the age of 20. The participants included smokers, former smokers and never smokers.

The study found that when compared to never smokers, current smokers experienced more difficulties falling asleep and more difficulties staying asleep. They were also more likely to wake up earlier than desired and they recorded less total sleep time overall.

Former smokers tended to report sleeping problems that were more similar to the never smokers than the current smokers.

Overall, the study found that almost 12% of smokers have major trouble falling asleep, compared to 4% of never smokers. Furthermore, over 10% of smokers wake regularly in the night, compared to 5% of never smokers.

Meanwhile, the study also noted that for each cigarette smoked that day, total sleep time that night decreased by 1.2 minutes.

"This analysis indicates that there are significant differences in sleep problems by smoking status. These results suggest that in addition to other negative health outcomes, sleep disturbances may be an additional negative health outcome associated with cigarette smoking.

"Since insufficient sleep has been associated with numerous physical and mental health problems, our results suggest current smokers may be more susceptible to these health issues than never smokers," the scientists said.

They added that these findings ‘strengthen the argument for the development and widespread implementation of programmes to help people with smoking cessation'.

Details of these findings are published in the journal, Psychology, Health & Medicine.