Pleasant smells can attract people to tobacco, while unpleasant odors—especially during sleep—may help people quit smoking.
WASHINGTON, D.C. — New research suggests that the mint flavor added to menthol cigarettes may make quitting smoking even more difficult.
Most smokers know they should give up the habit. However, nicotine in tobacco is highly addictive and makes quitting difficult. Scientists have found that this challenge is even greater for those who smoke menthol cigarettes.
The reason for this, explains Brandon Henderson, a neuroscientist at the California Institute of Technology (Caltech).
The Effect of Menthol on the Brain
Henderson’s team discovered that menthol enhances the effect of nicotine on the brain. Repeated exposure to nicotine causes the brain to produce more nicotine receptors.
These receptors are proteins located in cells that influence the activity of a chemical called dopamine. Dopamine plays a key role in transmitting signals in the brain and is especially associated with pleasure and reward. This mechanism is what makes smoking feel “rewarding” and leads to addiction.
To study menthol’s effect on this system, scientists conducted experiments on specially bred laboratory mice. In these mice, nicotine receptors glowed in different colors under fluorescent light:
- one appeared cherry red
- another appeared bright green
After exposure to menthol, researchers observed an increase in receptor numbers in the brain, particularly in the ventral tegmental area (VTA), which is associated with motivation and addiction.
Mice exposed to menthol had more nicotine receptors than those that were not exposed. This increase was similar to the effect produced by nicotine itself.
Henderson notes:
“This shows that menthol is not just a flavoring. It has real effects on the brain.”
Scientific Evaluation
These findings were also evaluated by Marina Picciotto, a neuroscientist at Yale University.
She stated:
“The most important finding is that long-term exposure to menthol can increase the number of nicotine receptors in the brain to the same extent as nicotine.”
She added that menthol may enhance nicotine’s addictive properties at the molecular level. However, further research is needed to understand how this affects human behavior.
Smells and Quitting Smoking
Another study suggests that adding unpleasant odors to cigarette smoke may help reduce smoking—especially if the exposure occurs during sleep.
This research was conducted by Anat Arzi, a neuroscientist at the Weizmann Institute of Science in Israel.
Arzi and her team had previously shown that people can form associations during sleep. In this study, they explored whether this type of learning could influence smoking behavior.
How the Experiment Was Conducted
Smokers were exposed to different odor combinations:
- cigarette smoke + rotten egg smell
- cigarette smoke + rotten fish smell
Participants were told that the experiment might help reduce smoking.
Some participants experienced the odors while awake and understood what was happening. Others were exposed to the smells only during sleep.
Since smells rarely wake people up—unlike sound or light—this method proved to be more effective.
Sleep Stages and Their Effects
Participants were exposed to odors during different sleep stages:
- Stage 2 sleep (the longest stage)
- REM sleep (the stage associated with dreaming)
A control group slept without exposure to any odors.
Researchers then monitored how much each participant smoked over the following week.
Results
Participants exposed to unpleasant odors during Stage 2 sleep showed a significant reduction in smoking.
Arzi stated:
“The reduction was around 30%.”
This effect lasted throughout the week.
In contrast, those exposed during REM sleep showed weaker effects—only on certain days.
Participants who experienced the odors while awake showed no change in their smoking habits.
Conclusion and Future Research
Arzi concluded:
“Learning during sleep can influence behavior while awake.”
The study was published in the Journal of Neuroscience.
However, researchers note that the experiment lasted only one night, and smoking behavior was tracked for just one week. Future studies should examine how long these effects last.
This is particularly important because tobacco addiction remains a major global health issue. For example, in the United States alone, smoking is responsible for approximately one in five premature deaths.
Final Thought
For this reason, scientists must continue to study the causes of tobacco addiction and develop more effective methods for its treatment.