Tuesday 阅读理解 A

How to pick music that will help you fall asleep

Getting enough sleep is necessary to good health, but now millions of people have a hard time getting to sleep. Many of us turn to quiet music, hoping that will calm ourselves down and make us relaxed. Music won't cure your insomnia , but it can provide short-term relief: There's even evidence that listening to music before sleep might improve sleep quality. So which tunes are actually the most helpful?

The answer, of course, depends largely on yourself: You're not going to fall asleep to a song if you can't stop thinking about how much you hate it. But if you want to make a sleep playlist, there are a few guidelines you should follow.

First, it's generally agreed that lyrics （ 歌词 ） are not recommended, as they're likely to excite our brains into more activity. Lyrics tend to remind of people or events in our lives and that can drive anxiety or deep thought. Dr. Nancy Irwin, a psychologist who specializes in sleep health, advises listening to instrumental music instead, particularly low instruments like the cello or the double bass.

Second, if you don't want to listen to music, noise is also an option. You've probably heard of white noise. It contains all the available frequencies （ 频率 ） of sound at the same intensity （ 强度 ）, which is great for covering environmental noise. There's also pink noise, which is similar to white noise but decreases in intensity as the frequency increases. This makes it seem calmer, kind of like when a song has a lot of cello or bass.

At last, although noise machines, apps, and playlists are a classic fix for people who have trouble falling asleep, they're not perfect: When you rely on the same sound for sleep, you'll finally have an even harder time getting to sleep if the sound isn't there. That's not advisable in the long run.