Study: Individual sleep needs go beyond the eight-hour rule

Good, deep sleep is a cornerstone of overall health and daily performance. However, the widespread belief that eight hours of sleep is the ideal and necessary amount for everyone proves challenging for many individuals.

In this context, psychiatrist and director of the Sleep and Cognition Center in Boston, Dr. Tony Cunningham, has challenged the common assumption that people must sleep eight hours a day. He emphasizes that each person has a unique biological rhythm that determines their individual sleep needs, noting that sleep quality may be even more important than sleep duration.

Speaking to the American network CNN, Cunningham explained that sleep quality is governed by two main forces: sleep pressure and the circadian rhythm. Sleep pressure—or the drive to sleep—increases the longer the body stays awake and decreases during sleep, much like the sensation of hunger. He therefore stresses the importance of going to bed when this pressure is high.

The circadian rhythm, the body’s internal biological clock, sends signals of alertness and sleepiness throughout the day. Feeling a sudden burst of energy late at night after staying up is evidence of this rhythm at work. According to Cunningham, high-quality sleep occurs when sleep pressure and the circadian rhythm are in sync.

To improve sleep quality, the expert advises waking up at the same time every day, describing this habit as more effective than maintaining a fixed bedtime. Regarding sleep duration, Cunningham notes that needs vary widely: some people function well on five or six hours, while others may require nine, ten, or even eleven hours, depending on their physiology.

To determine one’s ideal amount of sleep, he recommends following two steps: keeping a consistent bedtime and waking up naturally without an alarm. He explains:

“Go to bed, hide your clocks, block out the light, use a noise machine if you want, wear an eye mask—do whatever makes your bedroom free of time cues, then sleep and let your body wake up on its own.”

He adds that naturally waking up at the same time after a few days will reveal the optimal sleep duration.

In conclusion, Dr. Tony Cunningham stresses that success lies in understanding one’s individual biological rhythm. The goal, he says, is high-quality sleep and natural awakening—not rigid adherence to the traditional eight-hour rule.