Sleep Stages

There are many stages of sleep, and here we will go through each of them to explain what they mean.

Stage 1 mostly severs as the transition between sleep and wakefulness. During Stage 1 sleep, your brain and body relax. Your breathing becomes more regular and your muscle activity gradually decreases although you may make some jerky movements just as you pass from wakefulness to sleep.

SEVERS

Your eyes make slow rolling movements behind your closed eyelids as you settled down. This is a very light sleep, and you can be awakened quite easily. When awakened from this stage you might fell startled or may not even think you were asleep.

During stage 1, sleepers may suddenly feel out of balance as if they were falling, or make jerky movements with their whole body or limbs. Also they may experience dream-like flashes of images, hear loud noises, or feel they're hearing indistinct voices.

Most people who sleep normally stay in stage 1 for five minutes or less, but someone with insomnia might stay for much longer.

Stage 2 here the heartbeat and respiration slow and become very regular. The sleeper's body relaxes more deeply. Sleepers can still be aroused, but not so easily as when they're in Stage 1 sleep. Most sleepers spend about 30 minutes in Stage 1 and 2 before passing into Stage 3, which is a deep sleep. Stage 2 accounts for about 50% of all sleep time.

Stages 3 and 4 are deep sleep states, also known as "slow wave sleep" (SWS) because of the pattern of the brain waves they create on an electroencephalograph recording. The sleeper is very relaxed, with a slow regular heartbeat and breathing.

During deep sleep, sleepers are very difficult to arouse, and when you do wake them, they're groggy and slow to react to physical and verbal stimuli. There is no visible eye or muscle movement during these stages.

The sleeper is perfectly still, particularly as they progress to stage 4, which is the deepest and most restorative sleep. The body performs much of its necessary repair work during stages 3 and 4.

The first deep sleep of the night usually lasts about one hour in the young adult before the sleep cycle begins its first REM sleep episode. As people get older, their deep sleep episodes get shorten. They may also feel rested and rejuvenated after sleeping.

REM sleep is the time when you have most of your dreams. During this stage, your eyes move rapidly back and forth under closed eyelids. Here, you are temporarily paralyzed, apparently Mother Nature's safeguard to prevent the physical acting out of dreams.

Although researchers still aren't sure why, they know that brain blood flow increases during REM sleep, heartbeat speeds up and breathing rate increases. Sleepers usually spend about 90 minutes in the first 4 stages of sleep before passing into the first REM sleep episode of the night.

In successive NREM-REM cycles, the REM sleep episodes become progressively longer, with the final REM episode lasting as long as an hour. REM sleep accounts for about 20-25% of total sleep time in a normal adult.

Sleep Stages

SEVERS