We spend about one-third of our lives asleep, so it’s no wonder that for centuries we have been searching for ways to learn while we slumber. Now a new study from the Weizmann Institute in Israel suggests that certain kinds of mental conditioning applied during sleep may induce us to change our behavior; information that could be vital in helping individuals kick bad habits.
Researchers Prof. Noam Sobel and Dr. Anat Arzi found that when they exposed subjects to a tone followed by an odor, subjects would soon exhibit the same response to the tone as they would to the odor, suggesting that in the case of smelling, the sleeping brain acts similar to when it is awake.
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Pairing bad smells with bad habits
Building off research from 2012 Sobel and Arzi found that associative conditioning – a type of learning in which the brain is trained to subconsciously associate one stimulus with another – could occur during sleep by using an odor as the unconditioned stimulus.
Encouraged by their previous results and eager to put their research to good use, the team’s most recent study was designed to determine whether smells would be able to influence smokers’ habits. To test this theory, the researchers exposed the sleeping smokers to pairs of smells – cigarettes paired with the smell of rotten eggs or fish – then asking them to record how many cigarettes they smoked the following week. The results revealed that following conditioning during sleep, the smokers reduced their cigarette intake by about thirty percent.
Evidence that scent is our connection to the outside world as we sleep
While most research has largely discredited traditional “sleep learning” as we know it, Sobel and Arzi suggest that olfactory conditioning looks promising. This is especially true for addiction research, since the brain’s reward center, which is involved in addictive behaviors such as smoking, is closely interconnected with the regions that process smell. These regions, they say, not only remain active when we sleep, but may even enhance the information we absorb during our slumber.
To prove this theory, the researchers focused on cigarette smoking, a behavior that can be easily quantified. Sixty-six volunteers who wanted to quit smoking participated in the study. They were asked to fill out questionnaires about their smoking habits, and then those in the sleep group got to doze off in a special sleep lab where they were closely monitored. During certain stages of the sleep cycle, subjects were exposed to the paired smells – cigarettes and foul odors – one right after the other, repeatedly throughout the night. Interestingly, the subjects were unable to recall the orders when they woke up, but reported smoking less over the course of the next week, while those who were exposed to the paired smells in an awake state did not reduce their nicotine intake.
Specifically, the researchers noted that the best results occurred during stage 2, or non-REM sleep, when dreaming is very rare and brain activity very high, supporting earlier findings that suggested that we forget most of what happens in our dreams. Conditioning that occurs during the “memory-consolidation” stage, however, may stick.
Arzi explains, “We have no yet invented a way to quit smoking as you sleep. That will require a different kind of study altogether. What we have shown is that conditioning can take place during sleep, and this conditioning can lead to real behavioral changes. Our sense of smell may be an entryway to our sleeping brain that may, in the future, help us to change addictive or harmful behavior.”
Photos: Examined Existence