As the holiday season approaches and schedules become more hectic, getting enough sleep can feel increasingly difficult. While many experts recommend adults get between seven and nine hours of sleep each night, that guidance is based on averages — not individual needs.
Research consistently shows that sleeping fewer than seven hours a night can raise the risk of obesity, high blood pressure, heart disease and other chronic conditions. Studies have also linked very short sleep, especially five hours or less, to long-term health problems. But focusing only on hours slept may miss a bigger picture.
Tony Cunningham, a clinical psychologist and director of the Center for Sleep and Cognition in Boston, says sleep quality is just as important as sleep duration. According to Cunningham, the body relies on two key systems to regulate sleep: sleep pressure and circadian rhythm.
Why Sleep Quality Matters as Much as Sleep Time
Sleep pressure, sometimes called sleep drive, builds the longer you stay awake and eases while you sleep. It’s similar to hunger — the longer you go without eating, the hungrier you feel. Going to bed when sleep pressure is high helps improve sleep depth and quality.
Circadian rhythm, often referred to as the body’s internal clock, controls when you feel alert or sleepy throughout the day. While light can influence it, the rhythm is primarily regulated by the brain. This explains why people sometimes feel a burst of energy late at night, even after being awake for many hours.
For the best sleep, these two systems should work together. Irregular schedules, late nights or sudden changes in routine can disrupt this balance and reduce sleep quality. Cunningham notes that waking up at the same time every day may be more helpful than forcing yourself to go to bed at a fixed hour — especially if you’re not yet sleepy.
Once a consistent routine is established, the body naturally begins to settle into its optimal sleep window.
How Much Sleep Do You Really Need?
While seven to nine hours is a helpful guideline, it doesn’t apply equally to everyone. Some people function best on five to six hours of sleep, while others need nine, 10 or even 11 hours to feel fully rested. Biology and physiology play a major role.
To identify your personal sleep needs, Cunningham suggests starting with a consistent bedtime — one where you can fall asleep within 20 to 30 minutes. If you lie awake longer than that, it may mean you haven’t built enough sleep pressure. In that case, it’s better to get out of bed and do something calming, such as stretching, meditating or taking a warm bath, until you feel sleepy.
The next step is to find a period when you can sleep without an alarm. Remove clocks, block outside light, reduce noise and let your body wake up naturally. Over the first few days, you may sleep longer than usual as your body recovers from sleep debt.
After several days, your ideal sleep duration becomes clearer. When you wake up at roughly the same time for three or four days in a row without external cues, you’ve likely found the amount of sleep your body truly needs.
Not everyone has the flexibility to try this, but for students on break or people taking time off work, it can be a valuable way to better understand and improve sleep health — especially during demanding seasons.