Sleep is like a five act play where going to bed late means missing the first few acts and getting up too early means missing the last few acts. We need all five acts with good performances by the lead actors; good performances require keeping to the script and taking cues from the Director to make it to all come together.
1. The Stages of Sleep, 'Lead Actors'. Light sleep, Deep Sleep, and REM Sleep, each with unique roles to play.
2. The Sleep Cycles, 'The Acts of the Play'. Typically five 90-100 minute acts per night.
3. The Master Clock in the Brain (SCN), 'The Director' . Our master clock in the brain, the suprachiasmatic nucleus - SCN for short - is the Director. He sets the timing for each act based on the requirements of our Circadian Clock. Everything runs smoothly unless or until that script gets changed by external events.
Sleep Basics III
Sleep's Lead Actors - Stages of Sleep and Their Roles (Light, Deep & REM sleep)
Sleep's Lead Actors
We have two types of lead actors in Sleep: three Non-Rapid Eye Movement (NREM) sleep actors and one Rapid Eye Movement (REM) sleep actor.
Light Sleep (NREM Sleep Stage 1*)
A minor actor, this actor is more of a stage hand who helps prepare us for sleep. Known for dozing off but not yet being fully asleep. We'll ignore this actor for now.
Light Sleep (NREM Sleep Stage 2*)
Recently recognized for it's role in memory.
Deep Sleep (NREM Sleep Stages 3 & 4)
Also known as deep wave sleep or slow wave sleep.
Best known for rest, repair, rejuvenation (energy), and more recently, brain detoxification.
Essential for preserving and enabling the capture of new memories.
REM Sleep.
Also known as our dream sleep stage.
Well known for overnight therapy for emotions, reactivity, depression, and anxiety.
Integrates memories and past experience for learning and creative problem solving.
Sleep's 5 Acts - The Script for Each Sleep Cycle
The Five Acts
Our sleep runs in roughly 90 minute cycles, averaging 5 cycles per night. Think of it as a 5 Act play that averages 7 to 9 hours on a good night. (The actual length of each cycle changes over the night with some reaching 100 or more minutes.)
On a good night, it's like a well produced Broadway play. On a bad night, the actors are temperamental, sometimes refusing to show up for an act or two. Or they do show up, but their speeches are cut short and or they mess up their lines! Specifically: With insufficient sleep, they run out of time. With poor quality sleep, some processes are compromised and cannot be performed as well.
During each cycle, we pass through the different sleep stages (called actors in this analogy). The two Diva's are Deep Sleep and REM Sleep, each with very different roles to play. They're happy to share the stage with Light Sleep but their peak performances are at different times of the night.
Light sleep quietly takes the stage throughout the night.
Deep sleep owns the stage in the early sleep cycles and does not shows up in later acts.
REM sleep may appear early on but peaks in later acts, taking center stage closer to the morning hours when Deep Sleep is no longer around.
If we come late (go to bed after our normal time) or leave early (get up before usual), we miss performances from the early or last acts of the play. Essential processes are either missed or left unfinished. Immediate short term implications can be obvious (fatigue, foggy brain, falling asleep while driving, even higher rates of cardiovascular events). When it happens regularly, thee long term effect take time to show up. There is a stealth effect creating serious risks for our future-self.
The Actor's Roles
Each Stage of Sleep - each actor - has essential, unique attributes to help repair and detox, reset, rejuvenate, and re-calibrate our body or brain. All are equally important for different reasons.
Light Sleep (Stage 2)
Light sleep occurs throughout all sleep cycles. It has become a hot topic since researchers discovered its production of sleep spindles and their role in memory and routine motor skills. Two important light sleep functions include:
Consolidating memories through sleep spindles (a form of fast-forward replay that continues with deep sleep).
Activating the brain areas responsible for boosting routine motor skills such as physical performance in athletics or playing the piano.
Deep Sleep
During the early sleep cycles, deep sleep shows up much more than REM, providing restorative processes like replenishing our immune system and rebuilding muscle. We recently learned this now includes a brain detox process important to reducing Alzheimer's Disease risk. Important deep sleep roles include:
Cellular Renewal. Repairing and creating new cells in our tissues and organs.
Energy Restoration. Repairing, recycling, and creating new mitochondria - best known for regenerating energy to feed our brain and body, now recognized for their role in reducing numerous acute and chronic condition risks.
Memory Management. Transferring memories to long term storage depots thereby creating space for the next day's new memories to be captured.
Brain Detox. Flushing the brain of metabolic waste through the newly discovered glymphatic system; includes removal of beta-amyloid and tao proteins associated with Alzheimer's.
Miss your scheduled early hours of sleep and deep sleep runs out of time to finish the job! The actor must leave the stage before completing his lines.
REM (Rapid Eye Movement) Sleep
REM sleep has it's most time on stage during the cycles in the early morning hours.
REM not only makes meaning of our memories, but provides nightly therapy for emotional balance and impulse control. REM is essential to having a balanced mindset.
If we miss our usual morning hours of sleep, or get poor quality REM sleep, it cannot complete its many essential functions such as:
Internal Therapy for Emotional Balance. Replays difficult experiences through dreams to take the 'edge off' the emotional intensity of our memories; reduces risk for depression and anxiety.
Reactivity, Impulse Control. Restores and reinforces connections between our impulse control, executive brain areas (like the pre-frontal cortex), and the primitive, emotion driven brain areas (like the notorious amygdala).
Knowledge Creation, Learning, Creativity. Organizes, connects and integrates memories for learning and creative problem solving; forms associations with more distant linkages not obvious to the waking brain, hence those ah-hah moments after a good nights sleep!
Perception Acuity. Retunes our ability to accurately perceive and read both obvious and subtle social cues.
It's obvious when I don't get enough REM sleep. My buttons are easily pushed and my patience drops to an all time low!
In summary:
Deep sleep takes center stage during the early hours for rest, repair, detox, rejuvenation and memory transfer enabling new memory acquisition.
REM sleep takes center stage during that later, early morning hours, for impulse control, managing our state of mind and emotions, and organizing memory bites into knowledge for learning and creative problem solving.
Sleep's Director - Our Brain's Master Clock (The SCN)
Our brains and bodies evolved to run according to our Circadian Rhythms.
Every cell and organ in our body has it's own circadian clock! Each is programmed to do its job at pre-determined times throughout the day and night in a grand 24 hour symphony; Our Master Brain Clock takes cues to reset each day in align with the natural rhythms of life. It then sends a message to all the other body clocks so everything is properly synchronized for the coming day and night.
The director of this play, our master brain clock, takes it's first big cue from morning light.
When our our eyes sense morning light through special receptors in our retina, these receptors (melanopsin cells) send signals directly to our master clock in the brain, the SCN. They even detect light when our are eyes are closed. That first morning light cues for both wake up and sleep preparation times!
The Director (the SCN) tells all the other organ and cell clocks in the body what time of day it is so they can anchor their program to the right time and synchronize with all the other clocks in our body. It's like a daily reset to the Universal Time Clock that keeps our global world synchronized.
However, the SCN can be easily confused. Example. When we use blue lights or too bright lights of any color late into the evening, the SCN resets for daytime, sending wake up cues. Instead of sleep triggering signals. Chaos ensues. The play goes off the rails.
This ability to anchor to the morning and evening lights of sunrise and sunset is not the only lever influencing our body clocks but it is one of the biggest levers we have to manipulate our sleep schedule and securing a good nightly performance!
Final Word
Please don't worry about reaching the ideal or enjoying a late night with friends or a good movie from time to time. If we build decent habits for our typical day, there's no reason to stress out about the occasional change up whether forced or voluntary. Life is meant to be lived!
Wishing you the best,
Janice
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