Many people assume that eight hours in bed guarantees rest, but medical science draws a clear line between how long you sleep and how well you sleep.

Time spent asleep matters, yet true renewal requires a balance of duration and restorative quality that few people achieve consistently.

Dr. Wendy Troxel, a licensed clinical psychologist and senior behavioral scientist at RAND based in Utah, emphasized the “really important distinction” between quantity and quality of sleep.

That distinction matters because it reframes the goal from simply filling the clock to cultivating conditions that support real renewal.

She highlighted a common lament: “Man, I’m sleeping enough, I got seven to eight hours, but I still wake up feeling groggy and not refreshed.” The takeaway is that hours alone do not guarantee vitality if sleep is fragmented or non restorative.

“There are many factors that can contribute to poor sleep quality, regardless of how many hours you slept,” Troxel noted. Stress, meals, caffeine, and stressors can disrupt sleep architecture even when time in bed looks sufficient.

“These include drinking alcohol, a ‘major contributor’ to poor quality or disrupted sleep, and consuming caffeine late in the day.” The pattern of late alcohol or caffeine intake disrupts deep sleep and leaves mornings marked by fatigue.

“Being stressed or feeling worried about something can also contribute to fragmented sleep, as can phone use at bedtime.” When worries accumulate or screens draw attention, the mind stays alert and the body loses the opportunity to enter restorative stages.

Troxel addressed the belief that women need more sleep than men, noting research supports it only slightly, by about 10 to 15 extra minutes per night. “What we absolutely know is that women’s sleep quality often suffers more than men’s,” she said.

“Women are also twice as likely to have insomnia compared to men, and their risk for sleep disturbances “skyrockets” during the menopausal transition.” This reality matters for personalized guidance on when to seek help and how to optimize rest.

For those who claim they sleep better with fewer hours of sleep, and feel sleepier when they get the seven to nine hours, Troxel said this is not proof they need less shuteye. “It’s simply that their body is not used to it,” she said.

Laboratory studies show sleep deprivation impairs judgment. “That means someone who thinks they’re fine with only four hours of sleep per night likely isn’t aware of the impact sleep deprivation has on their cognition and performance,” she noted.

For those getting less than the recommended amount, Troxel recommends small steps toward longer sleep. Adding about 15 minutes per night can gradually move the body toward a healthier circadian rhythm. “You will likely see benefits when you increase your sleep in small increments,” she said.

Quality sleep hinges on following a healthy lifestyle and a consistent sleep-wake schedule. Eating a nutritious diet free of foods that cause upset stomach or indigestion, especially in the late evening hours, can help improve sleep quality.

“You don’t want to be starving at bedtime, but you also don’t want to be trying to fall asleep on a full stomach while your body’s still actively digesting,” she said.

Exercise helps to promote quality sleep, and sleep improves exercise quality. Yet vigorous activity close to bedtime can disrupt sleep. “Exercise is very stimulating, particularly if it’s in a social environment, and that can disrupt sleep,” she said.

“Exercising earlier in the day is better.” For night owls, morning workouts may not align with their rhythm. “Those who are natural morning people are more likely to benefit from exercising earlier,” she added.

“If you’re a night owl, don’t expect to love doing a workout first thing in the morning. That might not be consistent with your circadian rhythm.” Finally, she cautioned against sleep shaming. “Sleep-shamed” is unhelpful, and societal trends often undermine sleep-wake biology, which is largely outside personal control.