Composer John Williams once revealed how he pitched the iconic musical theme for Jaws to director Steven Spielberg, as Nigel Andrews relates in his aptly named movie guide, Nigel Andrews on Jaws: “Tapping out one-handed on a piano the creepy, chugging double-bass ostinato, Williams told the director, ‘Something stirs, an ominous growling, a rising semitone way down in the depths of the string basses…then the rhythm starts, slowly, slowly gathering momentum…then maybe, we add a tuba….’”

When the movie debuted in 1975, it was that riff—low, visceral, predatory—that terrified audiences as much as the huge mechanical great white shark. The two notes, E and F, sounded from a warren of bass strings and brass, like a reverberating heartbeat. Steady—then building hungrily into a sprint.

“‘You see, it was such a mindless thing, this idea,” Williams later told Andrews. ‘It had the effect of grinding away, coming at you, just as a shark would do, instinctual, relentless, unstoppable.’”

The notion that a musical score can make us feel something—in this case, raw, pulsing fear—is now well accepted. But understood or not, it creeps up in surprising ways. Take the conclusion of a study last summer by a team of researchers at the Scripps Institution of Oceanography. The report in PLOS One, by Andrew Nosal and colleagues, found that background music in shark documentaries, of all things, can be a subtle, “yet powerful source of fear that has been heretofore overlooked.”

In three experiments, the Scripps team presented more than 2,000 volunteers with either a 60-second video or an audio clip of swimming sharks—accompanied by uplifting music, ominous music, or silence—and then “asked a series of questions that measured their perceptions of sharks and willingness to conserve” them. In dramatic numbers, the people who watched the fish swimming to ominous music regarded them more negatively than those who saw the same footage with an upbeat score. Those who heard dark tones were more apt to apply adjectives like “scary,” “dangerous,” and “vicious” to the gliding vertebrates.” Those who heard the happier score were more likely to choose “peaceful,” “graceful,” and “beautiful” in their assessments.

Similar studies have arrived at parallel conclusions with regard to wine and even geometric shapes. Those who tasted wine while listening to background music that was “zingy and refreshing” tended to rate the wines in the same buoyant fashion; likewise, those who heard mellow music as they imbibed were more apt to describe the taste that way, too—and so on for music that was “powerful and heavy” or “subtle and refined.”

Why this matters in the case of sharks, say Nosal and his colleagues, is that documentaries meant to teach and inform may be sending the wrong message by way of musical undercurrent—teaching people to be more afraid of sharks than they should be, and harming conservation efforts in the process.

That’s not to say there isn’t a place for such ominous music. This afternoon, as the Senate takes up yet another iteration of its Obamacare-repeal bill, there will be mostly hushed and nervous tones in the Capitol building. I would suggest that someone pump in the Jaws theme to fill the void. The soundtrack, in this case, ought to match the stakes.

This essay appears in today’s edition of the Fortune Brainstorm Health Daily. Get it delivered straight to your inbox.