A person who has all six bad habits is more than five times as likely to die during a six-year period as one who is very clean-living, the journal PLOS Medicine reports.
Spending more than seven hours a day sitting, while doing little physical exercise and sleeping for more than nine hours, was almost as deadly.
The researchers said that unhealthy habits are behind a third of deaths.
They also found that participants who scored highly for combinations involving prolonged sitting and long sleep duration along with those who combine smoking with high alcohol intake, were the most likely to die early.
The Australian study adds to growing evidence that going to the gym in the evening doesn't cancel out the damage done by sitting all day in the office.
The University of Sydney researchers said:"This large study reaffirms the importance of healthy lifestyles."
More than 230,000 people aged 45 and over took part in the six-year study.
Dr Melody Ding, from the University of Sydney, said: 'To examine specific patterns of lifestyle risk behaviors, 96 variables - representing all possible mutually exclusive combinations of smoking, high alcohol intake, physical inactivity, poor diet, prolonged sitting, and short/long sleep duration - were created.
'Short and long sleep durations were separated as two different risk factors, as their associations with mortality may be explained by different mechanisms.
"This analysis investigated four established and two [new] risk factors, namely, prolonged sitting and unhealthy sleep duration, which may be added to behavioral indices or risk combinations to quantify health risk."
The new study comes after US researchers warned last month that excessive TV watching is linked to eight of the major causes of death, including cancer, liver disease and Parkinson's.
Researchers at the National Cancer Institute in Michigan discovered those who watch more than 3.5 hours of TV a day are not only at risk of cancer and heart disease - illnesses commonly associated with long term laziness - but also diabetes, influenza, pneumonia, Parkinson's and liver disease.
People who watched between three and four hours of TV a day were 15 per cent more likely to die from a common cause of death, compared to those who watched less than one hour a day.
And earlier this year, University of Cambridge researchers warned people who normally get more than eight hours of sleep are twice as likely to have as stroke as others - and women are particularly at risk.
The researchers said it was not clear whether these people were sleeping in because they were already ill or whether there is something about the extra hours in bed that is bad for us.
Independent sleep expert Dr Neil Stanley said having long lie-ins could be harmful for those who normally get little sleep. Keeping regular hours is the key, he added.
1 Alcohol consumption
2 Poor diet
3 Inactivity
4 Smoking
5 Spending more than seven hours a day sitting down
6 Sleeping for more than nine hours
A person who has all six bad habits is more than five times as likely to die during a six-year period as one who is very clean-living.
- Daily Mail
