There's no shortage of expert advice for improving your sleep: avoid caffeine and alcohol before bed, take a warm bath, turn in at the same time every night, keep your bedroom dark and quiet, stay away from screens, and so on. You might think you've crafted the perfect bedtime routine -- but how can you tell if it's working?

Two key metrics can help you determine whether you should change the way you wind down at night, according to June J. Pilcher, a psychology professor at Clemson University, who studies sleep.

Low sleep efficiency

One way to tell whether your nighttime behavior is helping you sleep is to compare the amount of time you spend in bed with the amount of time you spend actually sleeping. This ratio is known as sleep efficiency. If you regularly have trouble falling asleep, you might not be managing your habits in the best way, Pilcher says.

Many people fall asleep within five minutes, Pilcher notes, while others might take up to half an hour. There's no magic number, but once you feel like you've been lying awake for too long, get up.

Then, she says, "do something really boring," like read a dull book, until you feel sleepy. Avoid checking your phone or doing anything fun or active: "Vacuuming your house is not a good idea." 

Low sleep quality

Sleep researchers measure sleep quality in various ways, but you can track it yourself with a simple assessment, Pilcher says: When you wake up, rate the quality of your sleep on a scale of one to 10. If the number isn't as high as you'd like, re-evaluate your routine.

If you still aren't sleeping well (and you don't have a clinical sleep disorder), one counterintuitive method Pilcher suggests to improve both sleep quality and efficiency is to sleep less. If you're normally in bed for eight hours, try limiting yourself to seven hours for a trial period of two weeks. This will "force your body to take full advantage of a shortened sleep time," Pilcher says. Then, if you're falling asleep faster but still feel that you need more sleep in order to stay alert throughout the day, gradually increase your time in bed -- by about 15 minutes at a time, not a whole hour -- so that your body adjusts.

No matter what strategy you choose, it's best to first try to modify your behavior before you invest in an expensive new mattress or gadgets to help you sleep, Pilcher advises. "Often, just setting up a better behavioral response will fix the problem."