Official advice says that healthy adults require 7 to 9 hours of sleep every night for physical and mental health. Anything below this and you risk long-term sleep deprivation, which in turn ...

Is it safe to sleep for brief periods several times each day? Medically reviewed by Keri Peterson, MD Fact checked by Zerah Isaacs Individuals who are interested in a polyphasic sleep schedule may ...

I don’t know why." Leonardo da Vinci's sleep schedule included 20-minute naps every four hours. Da Vinci followed an extreme form of a polyphasic sleep schedule called the Uberman sleep cycle ...

Leonardo da Vinci's sleep schedule included 20-minute naps every four hours. Da Vinci followed an extreme form of a polyphasic sleep schedule called the Uberman sleep cycle, which consists of 20 ...