Smokers who indulge in their first cigarette shortly after waking up have an increased risk of developing lung and head and neck cancers, according to two new studies published in Cancer, a journal of the American Cancer Society. The findings may help identify smokers who have a greater risk of developing cancer. These smokers could then be more urgently targeted for smoking cessation programs.

The first studies to show a link between cigarette smoking and cancer were published back in the 1950s, but it wasn’t until 1980 that nicotine dependence was recognized by the American Psychiatric Association as a psychological and physiological problem. The new studies out of Penn State College of Medicine look at nicotine dependence, which in part can be determined by the amount of time elapsed before a smoker lights up his or her first cigarette after waking up in the morning.

“These smokers have higher levels of nicotine and possibly other tobacco toxins in their body, and they may be more addicted than smokers who refrain from smoking for a half hour or more,” says Joshua Muscat of the Penn State College of Medicine, who led the investigation.

Subjects who smoked their first cigarette between 31 and 60 minutes after waking up were more than 30% more likely to develop lung cancer; the odds increased to nearly 80% for those who smoked in their first half-hour awake. For head and neck cancers, subjects were more than 40% more likely if they indulged in the 31-60 minute window, and nearly 60% more likely for those who smoked in their first half-hour awake.

“One of the things we use to measure dependence is called the Heavyness of Smoking Index, which includes two questions,” says Dr. Richard D. Hurt, the director of the Mayo Clinic’s Nicotine Dependence Center, who is not affiliated with the new studies. “How much do you smoke, and how long after you arise do you have your first cigarette?”

Hurt also points out that waiting a little longer before indulging in a first cigarette of the day would mean fewer total cigarettes in a day. “The more dependent are more likely to be heavier smokers,” he says. “But you also have to look at how aggressively these people are smoking. Those who inhale deeper, hold longer, and smoke their cigarettes all the way to the end are receiving more of the harmful constituents of that cigarette.” This makes them more likely to develop cancer than those who smoke less aggressively.

The half-life of nicotine is relatively short – only two hours – so after six or eight hours of sleep, your body has gotten rid of nearly all of the nicotine you’ve inhaled the day before. There’s very little left in the body in the morning and the receptors in the brain are crying out for more nicotine. Those who are the most dependent need that cigarette earlier, and often smoke more cigarettes throughout the day, more intensely.

The takeaway here is about what you’d expect. “Stop smoking as soon as you can,” says Hurt. “We have more things to offer now than ever before. [You] can go to a physician or call a telephone quit line. We combine behavioral counseling with medications, which can double, triple, or even quadruple your chances of successfully quitting.”