Why Sleep Is the Clean-Up Crew for Your Brain

Sheila Ohlsson Walker Ph.D.

To boost mood, mental wellness and physical health, make sure to get your zzz’s!

THE BASICS

More than good old fashioned beauty sleep!Source: iStock / Getty, with permission

Although our brains comprise only 2 percent of our overall body weight, they consume roughly 20 percent of our daily energy expenditure. By day, the brain is highly active as it is in charge of coordinating and transmitting electrical information throughout the nervous system. At night it is 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. So what happens when we don’t get enough zzz’s?

Sleep deprivation spurs system-wide biochemical changes which, over weeks, months or years, can significantly impair our health, cognition, and mood. If you’ve had a rough night, or even a few strung together, don’t despair – restorative sleep can repay the debt. Here are the story and the science.

If the brain were an action-packed city, sleep would be its night-time 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 imaginary 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 the alert: “It’s time to clean up!”

The star players on our biological maintenance team are the glial cells, which locate and move out 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, removing 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 why sleep is so important for daily life:

Immune System: During sleep, our immune system regenerates and recharges its batteries allowing our bodies and brains to heal. A strong immune system defends against incoming attackers – viral or bacterial – blocking them altogether or reducing the severity of the symptoms. If we do fall ill, strong immunity accelerates recovery.
Metabolic Health: Inadequate or poor sleep increases levels of ghrelin (the hunger hormone), decreases leptin (the hormone that tells us when we’re full), and sends levels of cortisol (the stress hormone) up. 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 reality and gain perspective (e.g. pause, reflect, and label), and can thereby reduce anxiety and depression. In our everyday lives, particularly when under duress, our brains can trick us into catastrophic thinking and spiraling rumination. During 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 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 decreases inflammation, reducing risk for heart disease, stroke, high blood pressure, and just about every other major disease we struggle within the developed world.

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A personalized wind-down routine:

Adults need 7-9 hours of sleep per night, and teenagers need a minimum of 9 to 10. School-aged children and infants need more.
Tips for Your Physical Environment:
- At dusk, turn off or dim unnecessary lights.
- Stick with decaf after 2 pm.
- Cooldown your room, ideally to 65-68 degrees.
- Finish eating 3 hours before sleep.
- Opt for water or decaffeinated tea 3 hours before bed rather than alcoholic beverages.
- NO screens in the bedroom.
Tips for Your Mental Environment:
- Take a warm bath or shower (moves heat to the surface and lowers core body temperature).
- Try gentle relaxation exercises: stretching or light yoga.
  - Meditate: breathe slowly, 6 seconds in then 6 seconds out, and quiet your mind.
  - Journal: jot down racing thoughts onto paper and out of your mind.
  - Practice gratitude: reflect on 2 or 3 things and write them down.

At dusk, turn off or dim unnecessary lights.
Stick with decaf after 2 pm.
Cooldown your room, ideally to 65-68 degrees.
Finish eating 3 hours before sleep.
Opt for water or decaffeinated tea 3 hours before bed rather than alcoholic beverages.
NO screens in the bedroom.

Take a warm bath or shower (moves heat to the surface and lowers core body temperature).
Try gentle relaxation exercises: stretching or light yoga.
- Meditate: breathe slowly, 6 seconds in then 6 seconds out, and quiet your mind.
- Journal: jot down racing thoughts onto paper and out of your mind.
- Practice gratitude: reflect on 2 or 3 things and write them down.

Meditate: breathe slowly, 6 seconds in then 6 seconds out, and quiet your mind.
Journal: jot down racing thoughts onto paper and out of your mind.
Practice gratitude: reflect on 2 or 3 things and write them down.

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 and model adaptive and flexible behavior for those around us. 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!