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Blog Apr 10, 2020

Back to Basics: Why Sleep is the Clean-Up Crew for Your Brain

Photo by Vera Kratochvi

By Sheila Ohlsson Walker, Ph.D.  |   @DrSheilaOWalker

Welcome to the third article in our Back to Basics series: a conversation on the science of sleep. Our bodies and brains are integrated systems, and in this series we will illuminate how and why a handful of synergistic, simple, and scientifically grounded lifestyle choices offer protection from COVID-19 now and fortify mental and physical health for life.

Although our brains comprise only 2% of our overall body weight, they consume roughly 20% of our daily energy expenditure. By day, the brain is highly active processing and transmitting electrical information throughout the nervous system. By night, it is equally as active synchronizing neural mechanisms to repair damage caused by oxidative stress. Both processes are expensive to our energy stores, but the price is non-negotiable as we humans require a healthy functioning brain to survive.

For a clear image of what happens after a rough night of sleep, picture a young child. On the outside, we see irritability, impulsivity, fatigue, clumsiness, gastrointestinal issues and roller coaster moods. On the inside, these states are driven by an interactive cascade of hormonal, neuronal and metabolic signals, which undermine mood, self-regulation, digestion and system-wide health.

In less than a day, sleep deprivation spurs system-wide biochemical changes which, over weeks, months or years, can significantly impair our health, cognition and mood. Don’t stress if you’ve had a rough night, or even a few strung together – the weekly trend is what’s important to monitor. Moreover, restorative sleep can repay the debt. Here is the story and the science.


If the brain were an action-packed city, sleep would be its night maintenance team. Over the course of a day, litter (inflammatory molecules) accumulates on the sidewalks, and trash (tao and beta-amyloid proteins, risk factors for Alzheimer’s Disease) fills up the dumpsters. Exhaust fumes from cars, taxis and buses (oxidative stress) invisibly coat the sidewalks, streets and surrounding areas. As levels of garbage and grunge amass, adenosine (the biochemical that prompts a switch from wakefulness to sleep mode) begins to rise. When this switch occurs, the alarm bell at central headquarters rings to send the alert: “It’s time to clean up!”

The star players on our biological maintenance team are the glial cells, which locate and remove piled-up clutter, clearing the path for the other molecular-level street sweepers to do their jobs quickly and effectively. Glial cells set the stage for a sophisticated and mission-critical deep clean, clearing litter from the sidewalks (pruning unnecessary synapses), recycling glass and paper (protecting, nourishing and insulating neurons), and eradicating grit and grime (reducing inflammation).

Now that you know the science, here’s how sleep is important for daily life:

  • Immune System: During sleep our immune system regenerates, allowing our bodies and brains to heal. Strong immunity helps us fight viral exposure, and if sick, reduces severity and accelerates recovery.
  • Metabolic Health: When sleep deprived, our primal evolutionary brain yells “I must be starving, I need food now!” Inadequate or poor sleep increases levels of ghrelin (the hunger hormone,) decreases leptin (the hormone which tells us when we’re full) and sends cortisol (the stress hormone) up, which over time increases blood sugar and insulin. This faulty signaling drives food cravings – so if you’re home-officing in the kitchen – watch out!
  • Mental Health: Sleep improves our ability to reframe and gain perspective (e.g. pause, reflect and label, thereby reducing vulnerability to anxiety and depression. In our everyday lives, and particularly when under duress, our brains can trick us into catastrophic thinking and spiraling rumination. In the COVID-19 crisis, stress and anxiety are running high, so it’s more important than ever to control the things that we can. Remember: Name it to Tame it!
  • Cognitive Efficiency: While we sleep, the hippocampus, a key brain center for learning and memory, operates like a file transfer mechanism – integrating, organizing and consolidating information from the day. It is also the first area of brain function to show strain after a rough night. Sleep also synchronizes our “connectome,” the neural wiring that integrates our left and right hemispheres with our higher and lower brain centers, fostering cognitive malleability, reflection, creativity and deep learning.
  • Physical Health: Sleep is one of best insurance policies there is. It heals the body by decreasing inflammation, reducing risk for heart disease, stroke, high blood pressure, and just about every other major disease we struggle with in the developed world.

Here’s what you need to know to create a personalized wind-down routine:

  • Adults need at least 7-9 hours of sleep per night, children age 6-12 need 9-12 hours, and teenagers need a minimum of 8-11 hours per night.
  • Tips for Your Physical Environment:
    • At dusk, turn off or dim unnecessary lights
    • Stick with decaf after 2pm
    • Cool down your room, ideally to 65-68 degrees
    • Finish eating 3 hours before sleep. If you have to eat, choose protein over carbohydrates, which can elevate core body temperature and impair sleep.
    • Limit alcohol consumption and opt for water or decaffeinated tea 3 hours before bed
    • NO screens in the bedroom – charge electronics elsewhere:
  • Tips for Your Mental Environment:
    • Take a warm bath or shower (moves heat to the surface and lowers core body temperature – good for sleep!)
    • Try gentle relaxation exercises: stretch, light yoga
    • Meditate: breathe slowly, in and out, and quiet your mind
    • Journal: jot racing thoughts onto paper and out of your mind
    • Practice gratitude: reflect on 2 or 3 things and write them down

In closing, let’s join hands and strive to control the things we can. As the sun sets tonight, roll out the red carpet for your glymphatic system and let it go to work.

Waking up well-rested will elevate our awareness and presence, empowering us to flip our narratives, model adaptive and flexible behavior for our children and students, and cast ourselves as growing, learning, loving and connected mothers, fathers, spouses, teachers, caregivers, friends and family members.

This holistic feeling of balance and competence makes us a magnetic go-to for others seeking close proximity to people who feel like sunlight. And while physically distanced for now due to COVID-19, we need to be more socially connected than ever. Being with people who fill our emotional gas tanks – where love, trust and value are evident in tone, energy and words – is the name of the game. So put on some comfy PJ’s, fill your mind and heart with gratitude, and get cozy under the covers. We wish you a deep slumber and sweet dreams!

We are grateful for your time today. Please take a few moments to jot down some things you found helpful and integrate them into your Daily Recipe. If this blog entry captured your curiosity, you can learn more by reading “Why We Sleep” and for an appetizer, Matthew Walker’s TED Talk is excellent. We look forward to being with you next week for a conversation about why one of the most powerful, health-promoting tools in existence is your fork.


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