WEBVTT - Why Are Some Scents Soothing? 0:00:01.920 --> 0:00:06.560 Welcome to brain stuff, a production of I Heart Radio, Hey, 0:00:06.640 --> 0:00:10.520 brain stuff, Lauren Volga bam here. Close your eyes if 0:00:10.560 --> 0:00:14.560 it's safe to do so, and conjure up the following smells. 0:00:15.520 --> 0:00:19.880 Burst of citrus while peeling a juicy orange, the green 0:00:20.120 --> 0:00:23.560 piney scent of a fresh cut Christmas tree, or a 0:00:23.640 --> 0:00:28.200 warm waft of perfume from a blooming lilac bush is 0:00:28.280 --> 0:00:35.320 the very idea relaxing Stretching back millennia, ancient cultures like 0:00:35.400 --> 0:00:39.240 those in China, India, and Egypt recognized that certain aromas 0:00:39.280 --> 0:00:43.239 are deeply soothing, and folk healers have long prescribed sent 0:00:43.360 --> 0:00:48.120 it essential oils for treating stress induced conditions like anxiety, insomnia, 0:00:48.200 --> 0:00:52.040 and headaches. But science is still trying to figure out 0:00:52.200 --> 0:00:58.000 exactly how and why these potent aromas produce calming physiological responses. 0:00:59.200 --> 0:01:03.280 Our sense of smell is triggered when fragrance molecules attached 0:01:03.320 --> 0:01:08.360 to special cilia covered olfactory nerve receptors in our nasal cavity. 0:01:08.640 --> 0:01:12.600 Those receptors then send electrical signals directly to the olfactory 0:01:12.680 --> 0:01:16.039 cortex of the brain, which in turn talks to the 0:01:16.160 --> 0:01:20.040 memory and emotion centers of the brain like the hippocampus, amygdala, 0:01:20.160 --> 0:01:25.559 and frontal cortex, and a study published in the journal 0:01:25.640 --> 0:01:30.680 Frontiers and Behavioral Neuroscience strengthens the theory that some smells 0:01:30.720 --> 0:01:34.800 can act like nature's own anti anxiety medication, tweaking our 0:01:34.840 --> 0:01:38.040 brain chemistry in ways that mimic the effects of prescription 0:01:38.120 --> 0:01:43.920 drugs like valium and diazepam. In a series of experiments, 0:01:44.120 --> 0:01:47.920 Japanese researchers ran nice through mazes and other rodent stress 0:01:48.000 --> 0:01:51.760 tests while exposing them to an aroma called Lanella wall. 0:01:52.200 --> 0:01:55.600 It's the compound that gives lavender its sweet floral scent. 0:01:56.680 --> 0:01:59.960 From previous studies, they suspected the Lunella wall would lower 0:02:00.040 --> 0:02:03.360 anxiety levels in the mice, which it did, But the 0:02:03.360 --> 0:02:07.400 scientists also wanted to test a hypothesis that lavender's calming 0:02:07.440 --> 0:02:12.320 effect went straight from the mouse's nose to its neurons, 0:02:12.360 --> 0:02:15.880 so they included mice in the study that were anasmic, 0:02:16.320 --> 0:02:19.919 meaning they had no sense of smell. Those mice showed 0:02:19.960 --> 0:02:23.560 no effect from exposure to Linnell wall, approving that the 0:02:23.600 --> 0:02:29.400 olfactory system was definitely the delivery mechanism. Next, the researchers 0:02:29.440 --> 0:02:32.200 wanted to figure out whether Lennella wall was targeting the 0:02:32.240 --> 0:02:34.600 same receptors in the brain as some of the most 0:02:34.680 --> 0:02:41.480 common prescription anti anxiety medications. Drugs like valium, xanex, klonopin, 0:02:41.560 --> 0:02:44.640 and diazepam, are all members of the same drug family 0:02:44.880 --> 0:02:49.040 called benzo diazepines. One of the causes of clinical anxiety 0:02:49.080 --> 0:02:53.639 is overactive neuronal activity in the brain, and benzo diazepines 0:02:53.680 --> 0:02:57.680 can inhibit or calm down neuronal activity. They do this 0:02:57.800 --> 0:03:02.080 by binding to particular sites on rons called gammamno buttyrric 0:03:02.280 --> 0:03:07.160 acid or GABBA receptors. The Japanese researchers made a strong 0:03:07.240 --> 0:03:10.119 case that the smell of lavender acts on those very 0:03:10.320 --> 0:03:15.400 same GABA receptors. They did this by treating some of 0:03:15.440 --> 0:03:19.120 the mice with a drug that blocks GABA receptors, and 0:03:19.320 --> 0:03:22.960 when those treated mice sniffed the lunel wall, they didn't 0:03:23.000 --> 0:03:28.320 exhibit any calming effects. Lavender isn't the only aroma that's 0:03:28.360 --> 0:03:31.560 been linked to the same neuron receptors as potent anti 0:03:31.600 --> 0:03:35.880 anxiety drugs, though. A few years ago, German researchers tested 0:03:36.040 --> 0:03:39.680 hundreds of fragrances on GABA receptors in rodents and humans, 0:03:40.000 --> 0:03:43.320 and the big winner was jasmine, which delivered a gabba 0:03:43.360 --> 0:03:47.720 effect as powerful as sleeping pills and sedatives. Lavender and 0:03:47.840 --> 0:03:51.160 jasmine are the first ancient relaxation remedies to be tested 0:03:51.240 --> 0:03:54.840 like this, but several others may share a similar nosed 0:03:54.880 --> 0:03:59.880 brain mechanism, according to that Japanese study. Other compounds that 0:04:00.000 --> 0:04:03.200 have shown promising anti anxiety effects in mice and men 0:04:03.400 --> 0:04:07.120 include lemoning, one of the aroma compounds of citrus peels, 0:04:07.160 --> 0:04:10.360 and pining, one of the aroma compounds of pine trees. 0:04:11.800 --> 0:04:16.520 Aromas aren't universally relaxing, though, Since smells share such a 0:04:16.520 --> 0:04:21.080 close neurological connection to memories and emotions, their physiological effects 0:04:21.120 --> 0:04:26.720 can also be altered by our personal experiences. Like Pavlov's dogs, 0:04:26.720 --> 0:04:30.240 our brains can be conditioned to love or hate certain 0:04:30.279 --> 0:04:34.720 smells depending on our associations with them. For example, if 0:04:34.760 --> 0:04:37.440 you had a negative experience at a job or as 0:04:37.440 --> 0:04:41.279 a child scrubbing messes out with lemon scented cleanser, you 0:04:41.360 --> 0:04:45.919 might not find the odor all that soothing. A Research 0:04:45.960 --> 0:04:49.160 has shown that the olfactory system has the strongest direct 0:04:49.279 --> 0:04:52.359 line to the hippocampus and the amygdala, which are the 0:04:52.440 --> 0:04:56.160 memory and emotional centers of the brain. This is why 0:04:56.240 --> 0:05:00.680 sent memories can evoke such powerful feelings of nostalgia. A 0:05:00.800 --> 0:05:03.680 smell can carry us back to a specific time and 0:05:03.800 --> 0:05:07.480 place in ways that conscious thinking and remembering just can't. 0:05:08.360 --> 0:05:11.000 That might explain why we find the smell of baby 0:05:11.000 --> 0:05:15.000 powder so soothing. It summons feelings of security and love 0:05:15.200 --> 0:05:18.760 from deep in our earliest memories. But even that smell 0:05:18.880 --> 0:05:23.320 appears to have cultural variations. Americans associate the new baby 0:05:23.360 --> 0:05:27.440 smell with vanilla and powdery sense, while the French associate 0:05:27.480 --> 0:05:31.520 babies with the scent of orange blossoms. For some people, 0:05:31.680 --> 0:05:34.560 the smell of sunscreen is a stress reliever since it 0:05:34.600 --> 0:05:37.039 reminds them of care free summer days at the beach, 0:05:37.720 --> 0:05:40.640 and so if work is stressing you out, consider stowing 0:05:40.640 --> 0:05:43.239 a squeeze bottle of sp of fifty in your desk. 0:05:51.000 --> 0:05:53.520 Today's episode is based on the article what makes a 0:05:53.560 --> 0:05:56.640 sense soothing on houseuff works dot com, written by Dave Rouse. 0:05:57.000 --> 0:05:59.320 Brain stuff It's production offi Heart Radio in partnership with 0:05:59.320 --> 0:06:01.400 how Stuff Works to dot Com was produced by Tyler 0:06:01.440 --> 0:06:04.240 Playing and Ramsay Young. Four more podcasts from my heart 0:06:04.279 --> 0:06:07.200 Radio visit the i heart Radio app. Apple Podcasts or 0:06:07.240 --> 0:06:09.000 wherever you listen to your favorite shows.