People who smoke cigarettes as soon as they wake up have higher levels of nicotine than those who wait until after eating breakfast, regardless of how many cigarettes they’ve smoked, according to U.S. research. Scientists looked at smokers’ levels of cotinine, a nicotine by-product that reflects the risk of developing lung cancer, and found that those who’d eaten breakfast before smoking had a lower amount of this chemical. It’s not clear why, but the researchers from Penn State College think it could have something to do with the fact that those who light up first thing might have a greater need than those who can wait. In the study, more than 250 healthy people were observed, the BBC reports; among those who consumed 20 cigarettes a day, cotinine levels varied greatly, with the top levels nearly 75 times higher than the lowest. “Not all smokers are the same and approaches to smoking reduction may need to account for individual smoking behaviours such as the intensity and frequency of puffing, cravings, and physiological symptoms,” said report author Joshua Muscat. The highest levels were observed among those who smoked within 30 minutes of waking.