Understanding Sleep

In the last two phases of NREM sleep waves, brain function takes on a slower rhythm of ocean waves. In the second half of the night, the circulation slows down and the body shifts overnight between REM sleep and less sleep. Overnight you can go through the same cycle of four or five sleep levels per night but spend less time each time in a deep sleep.

During a sleep cycle, we spend about half of our sleep time in the N2 phase, where breathing and heart rate drop at night. As the night progresses, we will spend more time on REM (Rapid Eye Movement), which makes sleep more relaxing and refreshing while we sleep. We go around all the stages of sleep within 90-120 minutes and then wake up again. Each night we spend more time in deep sleep and more time in REM in the morning.

Stage N3 comes next, also known as Delta Sleep or Slow-wave Sleep, where delta brain waves are loaded slowly during this sleep phase. Stage N3 non-REM sleep, a deep sleep period when you need to feel refreshed in the morning.

They go through the non-REM and REM stages and sleep several times on a typical night, the longest and deepest phase occurring in the morning. The first part of this cycle is sleep non-REM sleep, which consists of four stages. Each of the first three stages falls into the “non-REM” phase, or rapid sleep and eye movement.

Non-REM (NREM) sleep, which does not show elevated eye movements, is divided into a series of four categories, sleep deprivation. Switching to arousal (N1), the first phase of sleep is defined as a pattern of the combined frequency with a low voltage that occurs about a minute to a minute before it begins to subside and eye movements are seen and the person first confesses with his head closed. The second stage is called sleep apnea, in which the heart rate and respiration rate drop as you lose consciousness and your body goes to deep rest, making it easier to wake up.

Deep sleep occurs in stage 3 when the brain and body functions descend to the lowest point of the cycle and blood is diverted from the brain to the muscles. When you go to REM sleep, the eyes go with the lid closed, and the brainwaves are like waking up.

Normal sleep includes deep sleep stages, deep sleep (also known as slow sleep wave sleep), dreams, and rapid eye movement when you wake up. REM (Rapid Eye Movement Sleep) is characterized by a dream state in which our brain and bodily functions are restored, including energy conservation and memory integration. During REM sleep (phase 4 of the sleep cycle) the brain activates and integrates memories, feelings, and activities that are critical to learning and higher levels of thinking.

Deep sleep and REM sleep involve profound changes in activity levels, and experts believe that these stages play a role in building healthy sleep that produces high-quality sleep. The fact that many parts of the brain are involved in waking up and falling asleep, including all stages of sleep, is another sign of difficulty sleeping.

Our brain regulates our waking cycles utilizing sunlight, which regulates hormones such as serotonin (our happiness hormone) and melatonin (our sleep hormone). These two factors influence how much sleep your body needs, which is reflected in your biological clock, time of day, and exposure to light when you wake up.

When scientists record brain waves during REM sleep, they find a function similar to what they see when they wake up. The thalamus is active during REM sleep and sends signals to the cerebral cortex, the brain envelope, which translates and processes short- and long-term memory details as well as images, sounds, and other senses that fulfill our dreams. The inner body clock, the basic organic clock that lets us know when it is time to wake up and when it is time to rest, is part of the hippocampus called the suprachiasmatic nucleus (SCN), which sends signals to tell us when it is time to go to bed or when to get up and move.

Specialized cells in the retina (eyes) make light and tell the brain in advance during the day or night, slowing down our sleep cycle. The brain stem, the base of the brain, and the pons medulla play a special role in REM sleep, where they send signals to relax important muscles in the posture and movement of organs, even if we do not achieve our dreams.

People who are blind and unable to connect their natural wake cycle with natural light can strengthen their stability by taking small amounts of melatonin at the same time of day.

Some sleep experts believe that the sleep cycle involves the second phase of slow-motion known as NREM-4, but the current term includes two slow-moving wavelengths into one phase (NREM-3). People with apnea reduced the N3 REM stage because their disturbed breathing caused sleep and shifted between stages N1 and N2 at night. Understanding the stages and cycles of sleep and their need to achieve hours of healthy sleep is important for us patients. We need to understand this information as we look to find out more about our sleep and our health.