When you go to sleep at night, you experience four stages of sleep. To feel the most well rested, generally, you need to wake up at the end of the sleep cycle.
The eyes are closed during Stage 1 sleep and you can be awakened without difficulty, however, if aroused from this stage of sleep, you may feel as if you havenʼt slept. Stage 1 may last for five to 10 minutes. During this time, you may feel like youʼre falling, which may cause you to jump suddenly, (called hypnic myoclonia).
During this light period of sleep the heart rate slows and the body temperature decreases. At this point, the body prepares to enter deep sleep.
Stages 3 and 4:
These are deep sleep stages, with stage 4 being more intense than Stage 3. This is when REM sleep occurs. These stages are known as slow-wave, or delta, sleep. If aroused from sleep during these stages, a person may feel disoriented for a few minutes.