"Ulrich has found that simply viewing representations of nature can help. In a study at a Swedish hospital, for instance, he found that heart surgery patients in intensive care units could reduce their anxiety and need for pain medication by looking at pictures depicting trees and water."
In one study, cancer patients were shown a video that included the sounds of waterfalls, creeks, and ocean waves. These patients, who were in chronic pain, experienced a 20-30% reduction in the stress hormones cortisol and epinephrine. In another important study, young adults in a dental office were exposed to water fountain sounds and experienced significant reductions in anxiety levels.
"These slow, whooshing noises are the sounds of non-threats, which is why they work to calm people," said Orfeu Buxton, an associate professor of biobehavioral health at Pennsylvania State University. "It's like they're saying: 'Don't worry, don't worry, don't worry.'"
"Our preference for aquatic environments may be explained by their critical role in our evolutionary history: Fresh water has always been essential to human survival, and salt water was and is a primary food source and portal for migration. Being drawn to aquatic environments, researchers say, was optimally adaptive for our ancestors—and the adaptation may still echo in our brains."
"Inward-focused attention can include worrying and rumination about things specific to one's self—patterns that have been linked to conditions involving psychological stress (including depression, anxiety, and post-traumatic stress disorder). Participants’ reaction times were slower when they listened to artificial sounds compared to natural ones, as well."