Smoking seems to have consequences on sleep too a new study reveled.

Scientists from Johns Hopkins University analyzed a number of 80 people while sleeping, half of them being heavy smokers (more than 20 cigarettes a day). All of them spent the night hooked up to an EEG (electroencephalogram) machine that recorded electrical activity in their brain during sleep. The researchers also recorded eye movements, muscle tine, respiration, electrocardiogram and leg movements.

None of them suffers from any disease related to smoking.

Participants were also asked about whether they got restful sleep or did not feel rested during the day.

The researchers found that smokers spent less time in deep sleep and more time in light sleep compared to nonsmokers.

“Smokers undoubtedly, when you look at the (medical) literature, have sleep-related difficulties. They have difficulty falling asleep and difficulty maintaining sleep. The question is why do they have this. It is possible that smoking has time-dependent effects across the sleep period. Smokers commonly experience difficulty falling asleep due to the stimulating effects of nicotine. As night evolves, withdrawal from nicotine may further contribute to sleep disturbance,” said study author Naresh M. Punjabi, MD, PhD, FCCP, Johns Hopkins University School of Medicine, Baltimore, MD.

Moreover, about 23 percent of smokers said they had restful sleep, compared to 5 percent of nonsmokers.

That is why the researchers encouraged people to quit smoking.

“The long-term effects of smoking on respiratory and cardiovascular health are well-known. However, this study is significant because it suggests that smokers may also be deprived of the much-needed restorative effects of sleep. This study provides yet one more reason to stop smoking or to never start,” Dr Alvin Thomas, president of the American College of Chest Physicians, said in a statement, according to Reuters.