4 stages of sleep Stage 1: This is the transition from wakefulness to sleep. It is a light stage of sleep, and people can be easily awakened during this stage. Brain waves are slower than during wakefulness, and people may experience hypnic jerks, sudden muscle contractions, during this stage. Stage 2: This is a deeper stage of sleep, and people are less responsive to external stimuli. Brain waves continue to slow down, and sleep spindles, short bursts of brain activity, occur during this stage. Stage 3: This is a deep stage of sleep, also known as slow-wave sleep (SWS). Brain waves slow down even further, and it is harder to wake someone up during this stage. This is the stage where the body repairs and regenerates tissues and muscles. Stage 4: This is also a stage of SWS, and it is the deepest stage of sleep. Brain waves are at their slowest, and it is very difficult to wake someone up during this stage. This is the stage where the body produces growth hormone, which is important for growth and development. Are you awake? Photography Beri Delgali