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.
Stage N2 occurs throughout the sleep period and represents 45-55% of total sleep time. Stage N3 (delta or slow wave sleep) occurs mostly in the first third of the night and constitutes 5-15% of total sleep time. REM represents 20-25% of total sleep time and occurs in 4-5 episodes throughout the night.