Read each description below and determine to which stage of sleep each pertains. Then, click and drag each box into the appropriate category below. Typlcally begins about 20 minutes after stage 1 Alpha waves dominate Sleep spindies occur Light sleep Vital signs are at their lowest levels Delta waves dominate Feeing a driting sensaton Beginning of dedline in respiration and blood pressure Stage 1 Stage 2 Stage 3 Stage 4

- Typically begins about 20 minutes after stage 1: Stage 3

- Alpha waves dominate: Stage 1

- Sleep spindles occur: Stage 2

- Light sleep: Stage 2

- Vital signs are at their lowest levels: Stage 4

- Delta waves dominate: Stage 4

- Feeling a drifting sensation: Stage 1

- Beginning of decline in respiration and blood pressure: Stage 2  

Explanation:

Sleep can be divided into two phases: 1-non-rapid eye movement (NREM) sleep and 2-rapid eye movement (REM) sleep. In turn, NREM sleep is divided into four stages (1 to 4). Stages 1-2 are referred to as “light sleep”, while stages 3-4 are known as “deep sleep”. The first NREM stage (normal length: 5-10 minutes) is the transition between wakefulness and sleep. During this stage, the brain produces high amplitude theta waves. During the second NREM stage (light sleep, 10-25 minutes), the body temperature drops, muscles are in a more relaxed state, the breathing and heart rate also drop. The third NREM stage (20-40 minutes) involves the emergence of delta waves and muscles are entirely relaxed. This period (stage 3) is a period of deep sleep, which is referred to as slow-wave sleep (SWS). Finally, the fourth NREM stage (10-60 minutes) is characterized by high amplitude delta waves, while heart and respiration rates slow dramatically.