CS - Rhythms of Life Lesson

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Rhythms of Life

alarm clockConsciousness is our awareness of ourselves and our environment. How conscious are you of yourself and everything in your environment in an average minute? We process much of life automatically, without really thinking about it. You may be able to type on a keyboard without thinking about each key, walk to your bedroom without thinking about where it is, or text a friend without looking at your phone. If you are awake, you are generally aware of yourself and your environment, so we would say you're in an alert state of consciousness. Some others include daydreaming, sleeping, hallucinating, drunkenness, and meditating.

What time of day are you sleepiest? When do you do your best thinking? Are you always hungry at a certain time? Your circadian rhythm, or 24-hour biological clock, causes you to experience these patterns of activity each day. Some people wake up early and think best in the morning, while others tend to have their peak of energy late at night. Each person's clock may be different, but it always works on a daily basis.

Bright sunlight and darkness help our brains know when to make us alert and when to make us sleepy. When bright light hits the retina, it sends a message to the Suprachiasmatic nucleus in the hypothalamus, telling the brain to stop producing melatonin (a hormone that causes drowsiness). Dim light tells the brain to begin producing melatonin. Modern artificial lights (including cell phone light!) can disrupt the circadian rhythm, making the brain think it's not yet time to produce melatonin, thereby keeping a person awake late at night.

We are also driven by cycles of activity while sleeping, going through distinct stages of sleep approximately every 90 minutes.

Sleep Stages: nREM-1 is when you're first falling asleep, you may experience hallucinations like the feeling of falling or floating; if awakened, you might not even realize you were sleeping. It's easy to wake up from stage 1 sleep; nREM-2 you're more asleep in this 20-minute stage, and your brain is experiencing sleep spindles (quick brain waves) in the midst of its slower sleep waves; nREM-3 is deep sleep, and it lasts for about 30 minutes. It's hard to awaken people from this stage, while their brain is making slow delta waves. Deep sleep is vital for growth and for restoring muscles; during this stage the pituitary glad produces growth hormone. People who don't get enough sleep often experience achy muscles and children who don't sleep enough will not reach their full growth potential.

After the deep sleep of stage nREM-3, your brain progresses back to stage 2 and then to REM sleep, during which your eyes dart back and forth under your eyelids and the rest of your body is perfectly still as you experience dreams. Thank goodness for your brainstem's ability to block messages during sleep! Your cortex is very active during REM sleep, but your body does not act out your dreams because the brainstem doesn't allow those messages to come through. This is the reason why REM sleep is also known as paradoxical sleep: your brain is active but your body is motionless.

sleep stages throughout a night's sleep including wake, REM sleep, Light sleep, and Deep sleep

Throughout the night, you'll progress back and forth between these stages, gradually spending more time in each REM sleep stage.

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