Happier people also find it easier to follow the core of a beauty routine—restful sleep, exercise, a balanced diet, time for fun with friends and family, and loving sex—the truest source of clear, bright complexions and eyes.

Listening right before work—or even when you’re working at home—may be a good habit. A recent study found that people solved problems in a more creative way when they listened to peppy music—in this study it was Mozart. “If you have a project where you want to think innovatively, or you have a problem to carefully consider, being in a positive mood can help,” says co-author Ruby Nadler, a psychology graduate student at the University of Western Ontario.

But don’t feel stuck with Mozart, Nadler says. Our taste is tied to our history. Experiments have even shown that one-year-olds remember music they heard in the womb. And people with severe memory loss from dementia often burst into perfect renditions of songs they first learned when they were fourteen, a time of self-discovery and strong emotions, when our amygdala tagged memories as important. 

This means that the fact that you’re clueless about opera or the latest pop scene shouldn’t let you drift away from music you do know and love.  

When branching out, there’s a simple test for how a song is likely to affect you. Your heartbeat responds to the beat of the music, says Joshua Berrett, Ph.D., a professor of music history at Mercy College in Dobbs Ferry, New York, and co-creator of musicandhappiness.com. So if you want to calm down, choose a slower beat; to rev up, the opposite.

To calm down to sleep: A resting heartbeat is normally between 60 and 100 pulses a minute. Music at a slightly slower tempo may relax you or lull you to sleep. Berrett suggests “Summertime” from the Miles Davis recording of “Porgy and Bess,” for an example of cool jazz, or for classical, Claude Debussy’s "Nuages." Chopin’s "Berceuse in D flat" is a grownup lullaby: “It has a pattern in the bass that imitates the rocking of a cradle,” Berrett says.  

To improve mood: Up the tempo a little to 100 to 120 pulses a minute for a calm, grounded joy.  A classic example is “California Girls” by the Beach Boys. But any music with sound elements or instrumentation you enjoy around that tempo could do the trick, Berrett says.