People who start smoking soon after they wake up are more likely to develop lung, head and neck cancer, compared to those who wait awhile before they light up, new research suggests.

Two studies examined whether the timing of a person’s first cigarette was associated with the risk of developing cancer. The Los Angeles Times reports the timing of a person’s first cigarette is considered a measure of addiction to nicotine.

One study looked at 1,820 smokers, including 1,055 who had head and neck cancer. The researchers found people who had their first cigarette within a half hour of waking up had a 59 percent increased risk of developing head and neck cancer, compared with those who waited for at least an hour to smoke. People who had their first cigarette between 31 and 60 minutes after waking up had a 42 percent increased risk of developing head and neck cancer, compared with those who put off their first cigarette for at least an hour.

The second study, by the same researchers at Penn State College of Medicine, included 4,775 smokers with lung cancer and 2,835 smokers without the disease. That study found smokers who started smoking within 30 minutes of waking up had a 79 percent increased risk of developing lung cancer, compared with those who waited at least an hour. Smokers who had their first cigarette 31 to 60 minutes after awakening had a 31 percent increased risk of lung cancer, compared with those who waited at least 60 minutes.

Both studies appear in the journal Cancer.