Why am I always tired if I get enough sleep?

A woman in bed covering her face with her hands
You may not known how long you actually sleep, especially if you don't sleep well. (Image credit: Oleg Breslavtsev via Getty Images)

Like most people, you will likely spend a third of your life in bed, and if all goes well, you'll sleep through most of it. But unless you participate in a sleep study, you'll have no clue what goes on while you're checked out, and you might not know how to gauge the quality of your slumber. You may not even have an accurate idea of how long you actually sleep, especially if you don't sleep well.

"People who describe themselves as "good sleepers' are better at estimating how much they have slept, compared to persons who classify themselves as "poor sleepers,'" said Dr. William "Vaughn" McCall, who leads the Department of Psychiatry and Health Behavior at Augusta University's Medical College of Georgia. 

So how do you know if you're sleeping well? The best measure of sleep quality — a combination of duration and efficiency — is how you feel the next day, McCall told Live Science.

Robert Roy Britt
Robert Roy Britt

Robert Roy Britt, author of "Make Sleep Your Superpower: A Guide to Greater Health, Happiness & Productivity," is a former editor at Live Science. He writes weekly about health and wellness on Medium.

"If you feel great, then your sleep is functioning just fine," he said.

But if you are often or always tired during the day, it may signify deficits in your sleep duration or efficiency. The signs will be familiar: You might struggle to get out of bed in the morning, or feel sluggish, unfocused or irritable in the afternoon. These can also be symptoms of other health problems, which is all the more reason to figure out what's behind any chronic daytime tiredness, and seek medical attention if you're not able to lessen or eliminate the symptoms.

The good news is, there are several science-backed ways to improve sleep quality, many of which can also help with depression, anxiety, chronic pain or other ills that could be intruding on your sleep

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Going deep

Experts say most adults need between seven and eight hours of sleep nightly. Some people can get by on less, based partly on genetics, but recent research suggests that less than seven hours, and particularly less than six, will not just leave you tired but also increase the risk of numerous physical and mental health problems.

But good sleep is about much more than the time spent in bed. 

Sleep comes in several repeated cycles of four stages that range from light to deep. During deep sleep, hormones and other chemicals are released to repair and rejuvenate the body's organs and tissues, and a garbage-collection system, called the glymphatic system, cleans the brain of misfolded proteins and other junk and toxins that accumulate during the day. During REM sleep, the phase of rapid-eye movement when most dreams occur, short-term memories are converted to long-term storage, and bad thoughts and negative emotions are dealt with and even shuttled away.

If sleep is cut short on either end, or disrupted during the night — even if you don't realize it — you rob the brain and body of these rejuvenation processes, as I explain in my new book, "Make Sleep Your Superpower" (self-published, 2022).

The length of time spent in each stage can be accurately measured only in a sleep lab, with devices that monitor brain waves, body temperature and other indicators of deep and REM sleep, said Dr. John Saito, a clinical doctor in sleep medicine, pulmonology and pediatrics at Children's Health of Orange County in California.

"It is impossible for the sleeper to assess accurately the quantity of his or her sleep," Saito told Live Science.

Try not to obsess

The threshold for good sleep efficiency — how much of your time in bed is actually spent sleeping — is about 85%, McCall and his colleagues noted in a study published earlier this year in the journal Scientific Reports. That means to get seven hours of actual sleep, as one example, a typical good sleeper might need a little more than eight hours in bed. While it's commonly thought that efficiency declines with age, the study found it's actually pretty stable from ages 30 to 60. 

Assuming you get sufficient hours of sleep, you still can't know how efficient it is. A sleep tracker could help. Well, sort of.

Commercial sleep trackers, available with some watches and activity trackers and even a ring, can offer a sense of sleep duration, efficiency and resulting quality. But research has found none of the leading brands to be fully accurate. In particular, these devices struggle to discern between light sleep, deep sleep and REM sleep. 

Another study suggests, with some irony, that obsessing over the data from a sleep tracker can cause stress that's bad for sleep.

"Unfortunately excessive self-monitoring and self-checking of your sleep with a sleep-tracking device can make matters worse, just as excessive self-monitoring of weight can be seen in persons with eating disorders," McCall said. "It is important to have a general idea about your sleep, but no need for daily checking over long periods of time."

As part of my research, I've been using a sleep tracker for several months, and it has helped me recognize patterns. When I sleep poorly — as measured by how I feel during the day — the tracker usually generates a low overall sleep score. When I feel good, the tracker typically indicates I slept well. But sometimes, the measurements are off, and I'm never sure why. When I feel good but the tracker surprises me with a low score, I get a twinge of anxiety that I know isn't good for me.

A sleep tracker may or may not be a smart solution for you. I try not to obsess over my readouts, but in general, they serve as a helpful reminder to stay focused on good sleep habits every day, so that my nights go well. Those better nights lead to greater energy, lower stress and more even emotions during the day — benefits of sleep confirmed by many studies.

How to improve your sleep quality

There are many tactics proven to help people fall asleep faster and sleep more efficiently, leading to better overall sleep quality. A good sleep strategy boils down to routines, consistently engaging in healthy habits and avoiding what I call sleep kryptonite — the dastardly outside forces and stupid things we do that hamper sleep.

Here are several helpful tactics you can choose from, compiled from suggestions by McCall, Saito and other experts:

  • Pick a consistent bedtime, and stick to it.
  • Get outside early in the morning, and spend at least two hours daily; bright daylight helps to set your body clock and optimize your sleep-wake cycle.
  • Avoid caffeine after early afternoon, and eliminate it if that doesn't help.
  • Avoid tobacco, nicotine and cannabis.
  • Get at least 20 to 30 minutes of daily physical activity, such as a brisk walk, yoga, weightlifting or any other movement that gets your blood pumping.
  • Learn science-based strategies to recognize, manage and reduce stress during the day.
  • If you nap, do it before late afternoon, and keep it to 30 minutes or less.
  • Avoid stressful activities in the late evening, such as reading or watching disturbing news or social media posts, discussing politics, or checking work email.
  • Turn off or dim all house lights in the last hour or two before bedtime.
  • Create a dark, cool and quiet sleep environment.
  • Wake up at the same time every day.

If those tactics don't do the trick, seek medical attention, Saito said, adding, "Identification and mitigating sleep problems early will improve short-term health and prevent long-term consequences."

Robert Roy Britt

Robert is an independent health and science journalist and writer based in Phoenix, Arizona. He is a former editor-in-chief of Live Science with over 20 years of experience as a reporter and editor. He has worked on websites such as Space.com and Tom's Guide, and is a contributor on Medium, covering how we age and how to optimize the mind and body through time. He has a journalism degree from Humboldt State University in California.