Stages of Sleep and Sleep Cycles Explained [Infographic]

Sleep Stages and Sleep Cycle Explained

Sleeping can be quite a complex process. Every time we drift off to sleep, the brain keeps working hard to make sure we wake up relaxed and rejuvenated. Sleep is made of five different stages, together which constitute one sleep cycle. In fact, the brain makes sleep happen just the way it keeps us awake alert through the day. Every night, we go through four or five sleep cycles, every 90 minutes on an average. It is normal to wake up, change sleep position, or get up for the bathroom between each cycle. The moment we get back to bed and fall asleep again, the next cycle begins, constituting the five stages. In infants and babies, each sleep cycle is shorter, around 50 to 60 minutes, and the number of cycles is more than five.

The Different Sleep Stages

Sleep stages can be classified into non-REM and REM. The first stage is the transitional period when sleep is the lightest, heartbeats decrease, and breathing and eye movements relax. In the second stage, heartbeats and breathing slow down further, body temperature drops, while the electrical activity in the brain occurs at a lower frequency. The third stage is when sleep gets deeper, heart rate and breathing become the lowest, and growth and restorative hormones are released. In the fourth stage, sleep is the deepest, almost like a coma. The person has no ability to toss or turn or wake up. Heartbeats and breathing are at the lowest, so is the body temperature. Night terrors, bedwetting, and sleepwalking usually happen in the fourth stage. The fifth stage is the only REM stage, called so because the eyes rapidly move from side to side behind closed eyelids. Dreams occur in this stage, but while the mind becomes active, the body is still immobile. This is the stage before waking up.

Factors Affecting Sleep Quality

A number of factors affect the sleep cycle, including age, sleep environment, medications and addictions, and internal body clock. Infants and babies sleep the longest and the deepest, while the elderly sleep the least. Ambient noises, lights, temperature, and the comfort of the bed also affect sleep quality.

Ways To Improve Sleep Quality

Sleep quality can be improved in various ways. These include sticking to a proper bedtime routine, maintaining sleep hygiene, limiting screen time, reducing consumption of caffeine and alcohol before bedtime, and eliminating environmental distractions. If there is a sleep disorder, melatonin supplements may be tried for an effective and natural remedy.