What Is Cardiac Catheterization? Cardiac catheterization is a diagnostic procedure that involves the insertion of a catheter (a long, thin, flexible tube) into the heart. The catheter is introduced into the body through a vein or artery, usually in the leg, and guided by the doctor toward the heart.
The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep. As the night progresses, REM sleep periods increase in length while deep sleep decreases. By morning, people spend nearly all their sleep time in stages 1, 2, and REM.
Each stage has different effects on your body - from physical restoration during deep sleep, to memory consolidation during dreams. All together, these stages add up to about 90-110 minutes, making up one complete sleep cycle. The Four Stages of Sleep