How Much Sleep Do You Need?

Dr. William Damon, the founder of Stanford University Sleep Medical Center, writes in his new book "The Promise of Sleep" that the key to falling asleep peacefully at night is consistently getting at least 8 hours of sleep per day. Some people might say, "That's fine, I usually sleep 12 hours on weekends." However, if on any given night during the week, you only sleep 5 hours, on average, your sleep quantity still falls short of the minimum standard.

While most sleep experts agree that taking a nap in the afternoon can help recover from the physical exhaustion caused by intense studying and work in the morning, sporadic napping or excessive daytime sleepiness cannot compensate for the damage caused by chronic sleep deprivation. A word of caution: After dozing off for half an hour, the body enters a deep sleep state, and upon waking up, one may feel sluggish and lethargic.

Therefore, experts recommend limiting the duration of dozing, napping, and afternoon sleep to within half an hour.