Stages of sleep

Every 60-100 minutes we go through a cycle of four stages of sleep

• Stage 1 is a drowsy, relaxed state between being awake and sleeping - breathing slows, muscles relax, heart rate drops
• Stage 2 is slightly deeper sleep - you may feel awake and this means that, on many nights, you may be asleep and not know it
• Stage 3 and Stage 4, or Deep Sleep - it is very hard to wake up from Deep Sleep because this is when there is the lowest amount of activity in your body
• After Deep Sleep, we go back to Stage 2 for a few minutes, and then enter Dream Sleep - also called REM (rapid eye movement) sleep - which, as its name suggests, is when you dream

In a full sleep cycle, a person goes through all the stages of sleep from one to four, then back down through stages three and two, before entering dream sleep

Source: Gregg Jacobs