Cigarettes could drain your brain as much as your body: Smoking may reduce your levels of dopamine, a brain chemical tied to reward, new research published in Biological Psychiatry suggests.

In the study, scientists discovered that smokers produce 15 to 20 percent less dopamine in their brains than nonsmokers

That’s partly why cigarettes can be so addicting: When you smoke, the nicotine activates receptors in your brain that release dopamine, which makes you feel a sense of pleasure, according to John Krystal, M.D., editor of Biological Psychiatry and professor at Yale University School of Medicine.

But after you stub out your cigarette, your dopamine levels drop back to their lower baseline, making you feel pretty crappy, he says. As a result, you may feel a lack of motivation, an inability to concentrate, or just moody.

So you look toward your next cigarette to provide that dopamine boost and make you feel better.

But when you quit your habit, you no longer receive that extra hit of dopamine. So your levels remain low.

As a result, the same blah feeling you experience in between cigarettes stretches out for a longer time, leading to other dopamine-related withdrawal symptoms, like irritability and fatigue, says Dr. Krystal.

Couple that with the physical symptoms of withdrawal—like headache, cough, and stomach pain—and the quitting process can feel endless.

But here’s the good news: In the study, after 3 months without cigarettes, the brains of former smokers began to produce just as much dopamine as nonsmokers produced.

This suggests that the post-quitting dopamine drop isn’t a permanent state—so if you can get through the first few months of kicking ash, it likely will get easier, says Dr. Krystal.

In the meantime, seek out other sources of reward that naturally raise your dopamine levels, Dr. Krystal advises. You’ll be more likely to quit smoking for good, he says.

In some ways, you’ll be rewiring your brain to get dopamine from other, healthier sources, instead of reaching for a cigarette.

For example, several studies have noted that physical activity increases dopamine, and even 20 minutes per day of medium-intensity cardio can do the trick.

Sex also counts, since you get a major dopamine surge during orgasm.

These healthier pleasures can help keep you smoke-free until your dopamine levels recover—and you’ll no longer find yourself reaching for a cigarette to feel good.