Early research suggests inhaling a pleasant aroma during sleep can significantly improve memory. In a small randomized control trial, participants exposed to the scent of essential oils for 2 hours every night over six months experienced a 226% improvement in memory compared to the control group.
"To my knowledge, that level of [memory] improvement is far greater than anything that has been reported for healthy older adults, and we also found a critical memory pathway in their brains improved to a similar extent relative to unenriched older adults," senior investigator Michael Leon, Ph.D., professor emeritus, University of California, Irvine, reported to Medscape Medical News.
Why it matters
The olfactory system is the only sense with direct input to the brain’s memory centers.
- Functional magnetic resonance imaging (fMRI) confirmed that participants given the scents improved their functioning of the left uncinate fasciculus, an area of the brain linked to memory and cognition — and an area that typically declines with age.
"The olfactory system is the only sense that has a direct 'superhighway' input to the memory centers areas of the brain; all the other senses have to reach those brain areas through what you might call the 'side streets' of the brain, and so consequently, they have much less impact on maintaining the health of those memory centers." —Dr. Leon
Notable: Olfactory dysfunction is the first symptom of Alzheimer's disease and is associated with various neurological and psychiatric disorders.
"I've counted 68 of them — including anorexia, anxiety, [attention-deficit/hyperactivity disorder], depression, epilepsy and stroke. In fact, by mid-life, your all-cause mortality can be predicted by your ability to smell things," Dr. Leon noted.
Closer look
The researchers randomly assigned 43 older cognitively normal adults (60 - 85) to receive either nightly exposure to essential oil scents or to a sham control with only trace amounts of odorants for six months.
- A diffuser delivered the essential oil scents.
- Oils used included rose, orange, eucalyptus, lemon, peppermint, rosemary, and lavender scents.
- No significant differences in olfactory ability were found between participants in the enriched and control groups.
- fMRI confirmed the enriched group improved their learning and memory by 226%.
- All participants received fMRI before the study started and six months later at its conclusion.
Reality check: Additional research is needed to verify these results.
