You already know that smoking is bad for you and that drinking too much alcohol may shorten your life. Now a new study says that spending too much time in a chair and depriving yourself of necessary sleep should join a short list of behaviors known to increase your risk of premature death.
Sedentary time and lack of sleep were damaging in their own right, but when combined with more traditional risk factors, they had a multiplier effect that made an early death far more likely.
The findings, published Tuesday in the journal PLOS Medicine, make clear that "some risk behaviors tend to cluster, particularly in certain patterns, and that the joint risk could be much higher than the sum of the individual risks," the study authors wrote.
For instance, smoking was the most dangerous single risk factor among the six studied — the small number of people for whom smoking was their only vice were 90 percent more likely to die during the course of the study than were people with practiced clean living across the board. People who reported high alcohol consumption — more than 14 alcoholic drinks per week — as their sole risk factor did not seem to be putting their lives in danger. But for those who combined heavy drinking with smoking, the risk of premature death was nearly tripled. And when lack of sleep was added to the mix, the odds of an early death were nearly five times greater — even though lack of sleep by itself had only a slight effect on mortality.
These numbers are based on the lives, and sometimes deaths, of 231,048 Australians from Sydney and rest of the state of New South Wales. They enrolled in the 45 and Up Study between 2006 and 2009, answering questions about their smoking history, eating and drinking habits, exercise routines, sedentary time and sleep duration. The study volunteers were tracked until the middle of 2014; during that time, 15,635 died.
When they joined the study, 7.2 percent of the participants were smokers, 19.1 percent were heavy drinkers, 17.2 percent had a poor diet, 22.9 percent got too little exercise, 25 percent spent more than 7 hours sitting each day and 23.1 percent got either too little or too much sleep. Nearly one-third (31.2 percent) of the volunteers did not engage in any of these risk factors, and 36.7 reported only one. However, 21.4 percent of them admitted to two of these bad habits, 8.1 percent admitted to three, 2.1 percent reported four, 0.4 percent had five and 0.04 percent engaged in all six.
Except for heavy drinking, each of the six behaviors was associated with at least a slight increased risk of death during the study period, the researchers found. Smoking was the most dangerous, followed by lack of exercise.
After accounting for factors such as age, gender, education and other demographic factors, the researchers saw a clear pattern: The more deviations a person had from a clean lifestyle, the greater his or her risk of premature death. Compared to people with no risk factors, those with just one were 27 percent more likely to die during the course of the study, and those with two had a 73 percent increased risk of death. At the other end of the spectrum, people with five risk factors were 4.61 times more likely to die, and those with all six were 5.38 times more likely.
Some combinations were more deadly than others, the researchers found. Those who blended insufficient exercise with prolonged sitting were 2.42 times more likely to die during the study, and those who were also guilty of sleeping for too many hours were 4.23 times more likely die by the time the study ended.