Definition of CASTLE for Kids. 1. : a large building or group of buildings usually having high walls with towers that was built in the past to protect against attack. 2. : a large or impressive house.ull Definition of CASTLE. 1. a: a large fortified building or set of buildings b: a massive or imposing house. 2. : a retreat safe against intrusion or invasion. 3. : 3rook. See castle defined for English-language learners.
The Science of Sleep. Sleep is one of the strangest things we do each day. The average adult will spend 36 percent of his or her life asleep. For one-third of our time on earth, we transition from the vibrant, thoughtful, active organisms we are during the day and power down into a quiet state of hibernation.
Following the N3 stage of sleep, a series of body movements usually signals an ascent to lighter NREM sleep stages. Typically, a 5- to 10-minute period of N2 precedes the initial REM sleep episode. REM sleep comprises about 20 to 25 percent of total sleep in typical healthy adults. NREM sleep and REM sleep continue to alternate through the night in a cyclical fashion. Most slow-wave NREM sleep occurs in the first part of the night; REM sleep episodes, the first of which may last only one to five minutes, generally become longer through the night.