Overview
- Researchers in Regensburg randomized 16 healthy adults to either inhale the scent of a freshly felled conifer for five minutes or hum Christmas songs for five minutes, measuring nasal nitric oxide before and after.
- Average nitric oxide levels rose after both activities, from about 42.7 to 46.1 ppb with tree scent and from 41.1 to 48.3 ppb with humming, though the changes were not statistically significant.
- Individual responses varied, with increases seen in roughly 44 percent for tree scent and 48 percent for humming, about 70 percent benefiting from at least one method, and roughly one quarter showing no measurable change.
- More than half of participants reported feeling more relaxed following the brief interventions, but researchers found no direct link between relaxation and the nitric oxide increase.
- The study was reported as preliminary, published in a complementary-medicine journal, and framed as a first step toward testing whether seasonal rituals may have short-lived biological effects.