Boost your brain while you snooze. How sleep scents may slow cognitive decline

The results of the study, published in the scientific journal "Frontiers in Neuroscience", offer hope for the development of uncomplicated, cost-effective, and efficient methods that could enhance cognitive functions in the elderly. The research, which involved 43 participants - both men and women aged between 60 and 85, suggested that diffusing the right scents in our sleeping environment could slow the decay of cognitive function and progression of dementia.

Earlier studies on mice revealed that exposure to several scents boosted their memory and neurogenesis (creating and differentiating new nerve tissue cells). Furthermore, the scientists noted, "The olfactory system is the only sensory system that directly projects to the limbic system", which plays a vital role in human memory and emotions. In contrast, other sensory systems indirectly connect with the limbic system through the thalamus.

The team of researchers divided the participants into two groups to check if carefully chosen sensory stimulation could slow cognitive function deterioration. The first group, consisting of 20 people, received a variety of natural oils, including rose, orange, eucalyptus, lemon, peppermint, rosemary, and lavender scents. The second group, serving as the control group, was given "dummy" oils containing minimal amounts of aromatic substances.

All participants were instructed to use scent diffusers to distribute fragrant substances for two hours every night over six months. As mentioned by Science Alert, they intermittently switched the scents being dispersed. The researchers then compared factors such as memory, verbal learning, planning, and attention shifting before and after the six-month study period using a set of neuropsychological tests.

The group exposed to the actual scents showed a considerable 226-percent improvement compared to the control group in the Rey Auditory Verbal Learning Test. This test measures memory, and there was also a significant enhancement in the functionality of the uncinate fasciculus, which links the amygdala and the prefrontal cortex. These are regions of the brain responsible for processing emotions and decision-making, among other tasks.

Researchers believe that even just a light fragrance stimulation at night could boost both cognitive and neuronal functions. However, this study was conducted on participants with similar psychophysical conditions. The researchers now aim to explore whether these results remain consistent if the method is applied to individuals diagnosed with a progressive loss of cognitive functions.