1 (Also called) civil year the period of time, the calendar year, containing 365 days or in a leap year 366 days. It is based on the Gregorian calendar, being divided into 12 calendar months, and is reckoned from January 1 to December 31.
40 FACTS ABOUT SLEEP YOU PROBABLY DIDN'T KNOW... (OR WERE TOO TIRED TO THINK ABOUT). - The record for the longest period without sleep is 18 days, 21 hours, 40 minutes during a rocking chair marathon. The record holder reported hallucinations, paranoia, blurred vision, slurred speech and memory and concentration lapses.
In a balanced order, nine healthy normal-weight men spent three nights in a sleep laboratory separated by at least two weeks: one night with a total sleep time of seven hours, one night with a total sleep time of 4.5 hours, and one night with total sleep deprivation (SD).