A recent study out of Japan shows that those who quit smoking and decrease their alcohol intake could improve their sleep quality. A University in Japan found that smokers who smoke a pack per day get 10 less minutes of sleep than those who do not smoke. Although the study only included men, the results are still important in understanding how sleep is effected by environmental and behavioral factors.
In addition to smoking affecting sleep, the study also found that those who had the equivalent of 1 and a half liters of beer per day were likely to wake up 1.5 times more in the middle of the night than people who drank less than 20 grams of alcohol per day.