What Is Sleep Quality?

If you’re attempting to get the perfect night of sleep, you probably feel like you’ve heard the term “sleep quality” a million times. But what does quality sleep mean?

Woman stretching her arms and smiling on the side of her bed, greeting the morning.
Oscar Wong/Getty Images

You’ve probably heard the phrase “sleep quality” thrown around in everything from magazine headlines to supplement ads to woeful conversations at the breakfast table, but sleep quality is a lofty term that many people may not fully understand. We know that “good” sleep is essential to overall health and well-being, but understanding how experts actually define “quality” can help us unlock better sleep and achieve that quality more often.

In short, “Sleep quality is the ability to have refreshing and restorative sleep, which improves our daytime function and overall health,” explains Dr. Funke Afolabi-Brown, sleep medicine physician and founder of Restful Sleep MD. “Getting the right number of sleep hours is ideal, but having restful sleep is also critical.”

A nutritious diet, a balanced exercise program, and mental self-care are widely regarded as critical to how you feel. Experts say good sleep is just as important to overall well-being. Sufficient uninterrupted rest allows the body to repair everything from injuries to immune system function, while also consolidating memories. Brown says that even if someone clocks a seemingly adequate amount of time in bed, if those hours aren’t restful, they may not be as health-promoting as they could be. “If you have nonrestorative sleep, increasing the number of sleep hours you get will not be as beneficial as finding out the cause (or causes) of poor sleep quality and addressing them,” she says. “Habits like drinking caffeine or alcohol before bed, eating heavy meals, and sleeping in a less optimal sleep environment can affect our sleep quality.”

What is quality sleep?

So what constitutes “good quality” anyway? Well, it’s not just one thing but a combination of many factors. According to researchers, while sleep quality may include time asleep, it also includes sleep latency (the time from lights out until you actually drift off and start the first sleep cycle), number of awakenings, and wake time. If you’re satisfied with all of these things, you’re probably experiencing good sleep quality.

“At its core, sleep quality is how well the sleep contributes to your being and feeling healthy, energetic, and metabolically refreshed,” says Dr. Chris Winter, neurologist, Sleep.com advisor, and author of “The Rested Child” and “The Sleep Solution.” “It’s basically how well your sleep works to maximize all of the processes that sleep plays a role in.”

How is sleep quality measured?

There are several ways to assess just how well you’re actually resting at night, and the methods range in invasiveness depending on the level of accuracy you’re after. “We can objectively measure sleep by using a test called a sleep study,” Brown says. “This is also known as a polysomnogram, which will look at your sleep architecture and also look for disorders like sleep apnea and restless legs syndrome. This test is ordered by your doctor if you have any symptoms concerning these conditions.”

For those who don’t have serious sleep troubles but suspect they may not be getting the most out of their rest, there are a variety of sleep trackers, both non-wearable, like the Sleep.com app, and wearable, like bracelets, rings, and other accessories that can offer quick insights. “The sleep trackers have a similar goal of objectively measuring your sleep by using algorithms to detect if you are in light sleep, deep sleep, or awake,” Brown says. “While these trackers are getting better at differentiating sleep from wake, they are not as accurate as a [monitored] sleep study and cannot tell you why your sleep quality is poor. Also, if you have insomnia or anxiety about your sleep, sleep trackers may actually make your sleep worse as you may start worrying about the data.”

“If you are interested in improving your sleep habits as part of your overall health, tracking your sleep may give you an idea of trends and opportunities for improvement,” she says. But for those who feel stress around sleep, Brown recommends a more holistic approach rather than fixating on the results of a sleep tracker.

Aside from sleep studies and trackers, there are some other tangible, gadget-free ways to assess how well you’re really resting. “The best way to determine if you have good quality sleep is to determine how you feel when you wake up,” Brown says. “Are you feeling tired or hitting snooze several times when you get up? Also, pay attention to how you feel during the day, such as feeling tired and sleepy during the day, needing naps frequently, or relying on caffeine to be alert.” Try taking a few minutes out of your day and jot this down in a bedside journal or your notes app. Looking back on your thoughts on your sleep night to night can help you hone in on your perfect night’s sleep.

How can you improve sleep quality?

Brown says that in addition to the usual sleep-disrupting suspects (alcohol, caffeine, light, a restless bed partner, etc.), stress and anxiety are major causes of nonrestorative sleep. “Conditions such as insomnia, sleep apnea, and restless legs syndrome, or chronic or acute pain are medical conditions that can contribute to poor sleep quality,” she adds.

Here are some actionable steps Brown recommends to ensure you get the best sleep quality possible:

  • Have a consistent sleep time and wake time.
  • Make sure your sleep environment is cool, dark, and noise-free.
  • Avoid caffeine, alcohol, or heavy meals before bedtime.
  • Use your bed only for sleep (and sex).
  • If you experience stress and anxiety, try to manage this during the day so that it does not affect your sleep quality.
  • If you are concerned about an underlying sleep disorder such as sleep apnea (typically presents with snoring), speak to your physician, as you may need a sleep study.