Kicking the tobacco habit is difficult, as any smoker will tell you. Various methods of suasion administered while he's awake are pretty useless. But new research done in Israel indicates that conditioning during sleep, with the help of particularly revolting smells, may help do the trick.
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In a paper published today in The Journal of Neuroscience, researchers from the Weizmann Institute exposed smokers to the smell of cigarettes paired with that of rotten eggs or fish, while the subjects slept. The volunteers did not remember the smells, but the following week, they smoked less.
No such effect ensued from exposure to the reek while awake, demonstrated Dr. Anat Arzi of the Institute’s Neurobiology Department.
“We have not yet invented a way to quit smoking as you sleep. That will require a different kind of study altogether," said Azri. "What we have shown is that conditioning can take place during sleep, and this conditioning can lead to real behavioral changes."
Why smell? Doesn't wake us
Arzi had previously shown that "associative conditioning" – Pavlovian-type learning in which the brain is trained to subconsciously associate one stimulus with another – could occur during sleep, if the stimulus used was smell. As opposed to other types of sensory stimulus, even really horrible odors do not wake us.
Her smoking study involved 66 volunteers who wanted to quit, but were not being treated for the problem. Note that what Arzi wanted to test was conditioning during sleep using smell as a stimulus: she chose smoking because it's simply to quantify.
First the volunteers filled out questionnaires about their smoking habit. Then in the sleep group spent a night in the department special sleep lab, under monitoring. At certain stages of sleep, they were exposed to paired smells – cigarettes and a foul odor – one right after the other, repeatedly throughout the night. They had no memory of the smells the next morning, but reported smoking less over the course of the next week.
In contrast, subjects who were exposed to the paired smells when awake did not smoke less afterward. Nor did sleepers exposed to cigarette smells and the two aversive smells unpaired, at random times.
Arzi found that the strongest result – 30% fewer cigarettes – appeared in volunteers who had been exposed to the smells during the stage called non-REM, or "stage 2". This is the stage characterized by light sleep: the heart rate and body temperature both drop. There is no eye movement and the sleeper may be easily awakened (stage 3 is the one in which people wake up feeling disoriented). The finding that the technique was most effective in Stage 2 sleep supported the group’s earlier findings - that people may forget their dreams, but conditioning impressed on our subconscious during the “memory-consolidation” stage may stick.
Meanwhile, earlier this week criminology researchers in Haifa announced that smokers may find it easier to kick the tobacco habit if they take omega-3 supplements from fish oil (not plant oil). The study was a limited one, on just 48 smokers, but found significant results. The reason is that smoking diminishes the concentration of crucial fatty acids in the brain. An imbalance of omega-3 can impair mental health, and the ability to cope with pressure and stress, which are famously associated with the urge to smoke.