When it comes to sleeping or lounging around, too much of a good thing can make you sick, especially if you're a middle-aged and older adult. New research revealed that in addition to traditional lifestyle risk factors, such as smoking and excessive drinking, sedentary behavior and poor sleep could also have a synergistic effect on health.

The study, published in this week's PLoS Medicine, found that a physically inactive person who sits for more than seven hours a day and has an unhealthy sleep pattern — getting less than 7 hours of shut-eye or sleeping more than 9 hours per night — are more than four times likely to die early than someone with healthier habits. "Evidence has increased in recent years to show that too much sitting is bad for you and there is growing understanding about the impact of sleep on our health, but this is the first study to look at how those things might act together," Dr. Melody Ding, lead author of the study, said in a statement. These things are formally known as non-communicable diseases (NCDs).

NCDs are a medical condition or disease that is non-infectious or non-transmissible, reportedly claiming the lives of about 38 million people every year; that's more than two-thirds of the world's annual deaths. Cardiovascular diseases, certain cancers, diabetes, and chronic respiratory diseases are the most common NCDs and are largely attributed to modifiable lifestyle behaviors: smoking, excessive alcohol use, lack of physical activity, and an unhealthy diet.

For the study, Ding and colleagues analyzed six years of follow-up data from an Australian cohort of more than 231,000 middle-aged and older adults who had completed a lifestyle questionnaire at baseline. They summed up the six health risk behavior measures — smoking, alcohol use, dietary behavior, physical inactivity, sedentary behavior, and sleep — for each participant in order to determine their overall lifestyle risk score; higher risk scores were associated with greater mortality risk. There were more than 15,600 deaths registered during the study period.

About a third of the participants reported a risk-free lifestyle, while 31, 37, 21 and 11 percent reported exposure to one, two, and three or more risk factors, respectively. People who participated in multiple lifestyle risk factors had in increased risk of early death.

"I was expecting that risk behaviors would interact with each other but I did not expect their synergistic relationship with mortality would be this strong," Ding told Medical Daily in an email. "For example, sedentary behavior, as a risk factor alone, is associated with 15 percent increased risk in mortality, and physical inactivity alone was associated with a 61 percent increase, but when the two co-occurred, even without additional risk factors, their associated risk increase was 142 percent. This was quite a striking finding for me."

Researchers say that more than 90 percent of the study participants had one of the most commonly occurring combinations of risk factors out of 96 possible combinations. Lifestyle risk combinations involving physical inactivity, prolonged sitting, and unhealthy sleep patterns, as well as combinations involving smoking and high alcohol intake, had the strongest associations with an increased risk of death.

"The take-home message from this research — for doctors, health planners and researchers— is that if we want to design public health programs that will reduce the massive burden and cost of lifestyle-related disease we should focus on how these risk factors work together rather than in isolation," study co-author Adrian Bauman said in a statement.

Ding added the findings reinforce the importance of adopting healthy lifestyles and suggests people follow their government’s health recommendations and guidelines, especially if you're aged 45 and older.

"I strongly recommend everyone compare their lifestyle behaviors with the guidelines to understand what needs improvement," she said. "Once you identify where the problems are and are willing to change, you may consider starting by using existing free programs, such as the Quitline and Get Healthy."

Source: Ding D, Rogers K, van der Ploeg H, Stamatakis E, Bauman AE. Traditional and Emerging Lifestyle Risk Behaviors and All-Cause Mortality in Middle-Aged and Older Adults: Evidence from a Large Population-Based Australian Cohort. PLoS Med. 2015.