Why 'good' sleep is about more than just the hours

• Sleep quality and sleep quantity are both essential for restorative rest and work together.
• Most adults need seven to nine hours of sleep, but individual needs can vary.
• Sleep quality is measured by how well you progress through the different sleep stages.

Sleep experts have long promoted the inherent need to get enough sleep. And while the message has always been that most adults need between seven and nine hours of sleep per night, there’s more to good sleep than the numbers on the clock. 

When some people hit their eight-hour target and still wake up feeling exhausted, and others can log a solid six hours and fire beautifully on all cylinders the next day, it begs the question: What matters more: sleep quality or sleep quantity?

Surprisingly, in the information age of trackers, scores and countless viral trends promising better sleep, it’s still difficult to discern which to prioritize. And while USA TODAY would like to put the topic to bed once and for all, it looks like the answer isn’t black and white — experts say healthy sleep lies somewhere between the two.

Sleep quantity: How much is enough?

Simply put, sleep quantity is the number of hours of sleep you get each night. And while an overwhelming majority of public health information online points to eight hours as the magic number for everyone, the truth is that there is no one-size-fits-all prescription for sleep. 

Noting that individual variability exists, Dr. Shelby Harris, psychologist, board-certified sleep specialist and Executive Advisor at BetterSleep, says, “Typically, we recommend between seven and nine hours per night, but there is no magic number that works for everyone. Even within this range, some people function better on seven hours, while others consistently need 9 plus hours to feel rested, sharp, and emotionally regulated.” 

For a good jumping-off point, the National Sleep Foundation offers the following guidelines.

• Infants (up to three months): 14–17 hours (including naps)
• Infants (four months to 11 months): 12–16 hours (including naps)
• Toddlers (one to two years of age): 11–14 hours (including naps)
• Preschoolers (three to five years of age): 10–13 hours (including naps)
• School-age kids/tweens (six to 13 years of age): Nine–11 hours
• Teens (14 to 17 years of age): eight–10 hours
• Adults (18 to 64): Seven–nine hours 
• Adults (65+): Seven–eight hours

While guidelines are helpful, Harris says, “I always encourage people to think about sleep quality, consistency and daytime functioning, not just the number on the clock, because [sleep] also varies as you age. Teenagers need more sleep than adults, and older adults often experience changes that can impact their sleep.” Beyond age, Harris notes stress levels, physical health, hormones, medications and mental health can also influence sleep needs across a lifetime. 

But sleep duration alone doesn’t tell the entire story.

​​Sleep quality: What is a good night’s sleep?

Fundamentally, sleep quality refers to how well you sleep. Matthew Walker, neuroscientist and professor of neuroscience and bioengineering at the University of Texas at Dallas, tells USA TODAY, “[Sleep] quality is the architecture inside the hours, not the hours themselves.” He goes on to explain that science measures [sleep quality] on four axes: 

• How fast you fall asleep 
• How often you wake during the night 
• How many micro-arousals fragment the underlying tissue of sleep
• Whether you progress uninterrupted through the four ninety-minute cycles of light, deep and REM that the brain depends on 

Regarding those sleep stages and their importance, Walker adds, “Each stage performs a different job — deep sleep clears metabolic waste and consolidates fact-based memory; REM rewires emotional memory and creative association — and a high-quality night is one in which the brain completes each cycle before the next begins.” 

What does good sleep look like in real life?

Sleep quality is often harder to define than sleep quantity, but according to Walker, truly restorative sleep tends to follow a recognizable pattern. He explains a good night’s sleep means: “You fall asleep within fifteen to twenty minutes. You wake fewer than twice. And you rise inside roughly the same hour window each morning, restored — not yanked out of unconsciousness when the alarm fires.” 

Walker adds that for most adults that pattern falls within seven to nine hours of sleep in a bedroom near 65 degrees, with no alcohol in the bloodstream and no phone within reach. “The honest scoreboard,” he says, “is the day after: the world arrives at its proper volume, your patience holds against ordinary irritations, and you forget you slept at all.” 

And while we’re on the subject of good sleep, experts caution against chasing perfection. “Good sleep in real life usually looks a lot less perfect than people expect,” says Harris. “It doesn’t mean you never wake up during the night (brief awakenings are more normal than people think) or fall asleep instantly.” The goal, she says, “isn’t perfect sleep every night, but building habits that support healthy, consistent sleep most of the time.” 

Sleep quality vs. quantity, which matters more?

“The two are not rivals,” says Walker. “They are the two oars of the same rowboat — pull only one, and you spin in circles, no matter how hard you row.” 

In other words, sleep quality and sleep quantity go hand in hand. They work together, not against each other. Sleep quantity gives your brain the time it needs to move through essential stages of sleep, including deep sleep and REM, while quality determines whether those stages remain uninterrupted and restorative. Walker says, “a fragmented eight hours stitched together by alcohol micro-arousals, undiagnosed [sleep] apnea, or a 2 AM phone glance can leave you more depleted than a clean seven, because the architecture inside those hours never had a chance to finish itself.” 

Ultimately, he says, “The ‘which matters more’ debate is the wrong frame.” The better question is not ‘which,’ but how you bolster both simultaneously. 

Likewise, Harris says that if she had to prioritize one, she would start with quantity for the same reasons: “The body needs enough time to complete the essential processes that happen during sleep, and there’s no real shortcut for that.”

Falling short on either can affect your health

Along with diet and exercise, sleep is widely considered the third pillar of health. Yet, research shows that roughly 30% to 50% of Americans regularly come up short. 

Of course, an occasional restless night may not be cause for concern, and most people experience them from time to time. Consistent short sleep, however, has been linked to measurable declines in cognitive performance and day-to-day functioning, while chronic sleep deprivation is associated with more serious long-term health risks. 

The short-term effects of sleep deprivation may include increased risk of: 

• Headaches
• Excessive daytime sleepiness/fatigue 
• Moodiness/Irritability
• Poor focus/concentration
• Impaired memory/information retention
• Delayed reaction times 

The long-term effects of sleep deprivation may include increased risk of: 

• Type 2 Diabetes
• Obesity
• Impaired immune function
• Heart disease
• Depression
• Anxiety 

4 changes you can make tonight to improve your sleep quality

According to the experts, the key to improving sleep quality lies in good sleep hygiene. 

Optimize temperatures

“Core body temperature has to fall by about a degree Celsius (1.8°F) for sleep to begin and hold, which makes a warm room the single most underestimated thief of deep sleep,” says Walker. So, to improve your sleep latency (the time it takes to fall asleep), try lowering the temperature in your sleep space to around 65°F. 

To further support temperature optimization, Walker recommends a warm bath before bed. “A warm bath ninety minutes before bed accelerates the drop [in your core body temperature] — counterintuitively — by pulling heat from the core to the skin and dumping it into the air,” he says. And plenty of studies have shown as much, linking warm baths and showers to shorter sleep latency and better sleep efficiency.

Maintain a consistent sleep-wake schedule 

“The circadian system rewards regularity and punishes drift,” says Walker. “Sleeping in on Saturday is a self-inflicted time-zone shift, and Monday morning is the jet lag.” Both he and Harris emphasize that one of the most effective ways to improve sleep quality is also one of the simplest: maintaining a consistent wake-up time, even on weekends. 

“A lot of people look for quick fixes like supplements or complex routines, but the biggest driver of better sleep is a stable wake-up time, even on weekends,” Harris explains. “That regularity helps keep the body’s internal clock on track, which makes it easier to fall asleep and stay asleep over time.”

Evict the phone 

While most of us use our phones to catch up and unwind at the end of the day, screen time habits can have a powerful (and detrimental) effect on our sleep. 

According to Walker, “Two hours of evening screen light suppresses melatonin (the sleep hormone) by roughly a quarter and delays its release by ninety minutes.” He explains that this is why “phones feel calming and act stimulating at the same time.” Essentially, our brain is still receiving signals to stay alert when our minds should begin to relax and prepare for sleep. 

Over time, that disconnect can exact a heavy toll on sleep. So, to protect your shut-eye, try skipping the late-night doomscroll altogether.  

Decline the nightcap

Though alcohol is widely used for sleep support, Walker cautions that it’s likely to do more harm than good as it metabolizes through the night. “Alcohol is a sedative, not a sleep aid — it knocks you unconscious quickly, then fragments [your sleep during] the second half of the night and blocks roughly a quarter of your REM sleep,” he says. So, save your forty winks and take a pass on the glass of wine after dinner. 

The verdict

Ultimately, a good night’s sleep isn’t just long — it’s refreshing and restorative. Getting enough hours doesn’t automatically mean someone is well-rested, and high-quality sleep cannot fully compensate for chronically getting too few hours. Both sleep quality and duration are essential, and neither can replace the other. Harris says, “The healthiest approach is really to focus on both rather than treating them as separate issues, and definitely consult a doctor if the issues persist.”