The circadian rhythm – it’s the natural, internal 24-hour regulation of the sleep-wake cycle of all living creatures. Moderated by sunlight and temperature, the cycle is essential for brain-wave activity, hormone production, cell regeneration – and it only happens when we’re asleep. A regular sleep cycle consists of four important stages that transition an individual from light sleep to deep slumber.
When an individual prepares to rest at the end of the day by closing his eyes and slowing his breathing, he enters into Stage 1 of non-rapid eye movement sleep (NREM). Known as dreamless sleep, it lasts for one to 10 minutes and can easily be disturbed. Stage 2 of NREM sleep then occurs for 20 minutes as the body decreases in temperature and slows the heart rate. This stage of light sleep is important as 45% of total sleep is spent here.
After 35 to 45 minutes of slumber, sleep disturbances are less likely to wake an individual entering Stage 3 of NREM. Brain waves begin to slow down and enlarge, while the brain’s natural file-transfer mechanism shifts memories from short-term to long-term storage. At the end of the total sleep cycle, Stage 4 or rapid eye movement sleep occurs. Lasting for only 10 minutes, it’s the deepest stage of sleep as heart and respiration rates increase and eyes rapidly move in all directions. The most vivid dreams or sleepwalking also occur during this stage. It’s important to prioritize a full night’s rest by allowing your body to follow through an entire sleep cycle.