08/08/2011 01:33 pm ET Updated Dec 06, 2017

Early-Morning Smoking Bumps Cancer Risk Even Higher

An early-morning smoker has a higher cancer risk than someone who first lights up later in the day, a new study suggests.

People who smoke within the first half hour of waking up are 79 percent more likely to have lung cancer than people who wait at least an hour after waking up to smoke, according to new research published in the journal Cancer.

People who smoke first thing after waking up also have a 59 percent higher risk of head and neck cancers, compared to people who wait a bit before smoking, according to the research. And researchers also found that the chances of developing cancer based on the time of the day of the first smoke were independent of other smoking habits.

So smokers are probably wondering -- why? Researchers aren't positive, but they do have their hunches.

Study researcher Dr. Joshua Muscat told the BBC that it could be because early-morning smokers have higher nicotine levels in their body, and could therefore be more addicted than smokers who are able to wait longer before smoking.

Meanwhile, Cancer Research UK's Professor Robert West told the BBC that early-morning smokers might smoke a cigarette more intensely than someone who smokes later in the day.

So "the sooner a smoker lights up, the more smoke is taken into the lungs, and the higher the level of exposure to cancer causing chemicals," West told the BBC.

Penn State College of Medicine researchers conducted two linked studies. The first was of 1,055 people with head and neck cancer and 795 people without, who all had a smoking history, MedPageToday reported. The second study involved 7,610 smokers, some who had lung cancer and some without.

In the U.S., smoking accounts for 80 percent of lung cancer deaths among women and 90 percent of lung cancer deaths among men, according to the National Cancer Institute. It also causes throat, esophagus, mouth, stomach, bladder, cervix, pancreas and kidney cancers, as well as acute myeloid leukemia.

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