The Cleaning Crews

Every Monday a large noisy truck passes through my neighborhood hauling away each household’s detritus of modern daily living: empty cartons, food wrappers, unread junk mail and cat fur vacuumed from the rugs, under the furniture, behind the doors (well, everywhere really). Trash collection is a luxury I tend to take for granted as long as the truck shows up on schedule.

Our body also depends on waste disposal systems to avoid buildup of metabolic by-products, excess fluids and toxic substances. The lymphatic system, which is composed of the lymph nodes, lymphatic vessels, the spleen, and the thymus, works around the clock transporting waste from the cells in our body to the bloodstream where it is filtered out by the kidneys.

The brain’s cleaning crew works the night shift. During sleep, the glymphatic system ramps up as cerebrospinal fluid (CSF) flows through channels in the brain, flushing away metabolic waste.

Efficient glymphatic function is essential for neurological health and memory consolidation. Accumulated waste products in the brain have been linked to mood disorders, impaired cognitive performance and increased risk of stroke and neurodegenerative diseases.

Along its route, CSF collects harmful by-products like beta-amyloid, a sticky protein fragment that naturally forms in the brain when larger proteins are broken down. If it's not cleared efficiently, beta-amyloid can clump together to form plaques between brain cells. Scientists believe that plaque build up disrupts communication between neurons and triggers inflammation, leading to Alzheimer’s disease.

The Link Between Sleep and Brain Health

Crucially, sleep quality directly impacts glymphatic efficiency. Studies show that poor or insufficient sleep impairs the system’s ability to clear waste, allowing toxic substances to build up. Chronic sleep deprivation is increasingly recognized as a major risk factor for cognitive decline and dementia.

But how do you know if you’re getting enough restorative sleep? Common signs include waking feeling refreshed, maintaining consistent energy levels throughout the day, and rarely needing excessive caffeine to stay awake. Adults typically need 7–9 hours of sleep per night, with good proportions of deep (slow-wave) and REM sleep.

To optimize glymphatic performance and restorative sleep:

• Stick to a consistent sleep schedule, even on weekends.

• Create a cool, dark, quiet bedroom environment.

• Wear a sleep mask and earplugs.

• Avoid caffeine, alcohol, and heavy meals close to bedtime.

• Avoid checking email or headlines before bed.

• Engage in regular physical activity, but not too late in the evening.

• Incorporate relaxation techniques like meditation, deep breathing or a ho-hum book to wind down at bedtime.

Prioritizing high-quality sleep is one of the most powerful strategies to protect your brain’s health—and to support your incredible glymphatic system working the night shift.

Sources:

• Iliff, J. J., et al. (2012). A paravascular pathway facilitates CSF flow through the brain parenchyma and the clearance of interstitial solutes, including amyloid β. Science Translational Medicine, 4(147), 147ra111.

• Selkoe, D. J., & Hardy, J. (2016). The amyloid hypothesis of Alzheimer's disease at 25 years. EMBO Molecular Medicine, 8(6), 595-608.

• Xie, L., et al. (2013). Sleep drives metabolite clearance from the adult brain. Science, 342(6156), 373-377.

• Rasmussen, M. K., Mestre, H., & Nedergaard, M. (2018). The glymphatic pathway in neurological disorders. The Lancet Neurology, 17(11), 1016-1024.

• Fultz, N. E., et al. (2019). Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep. Science, 366(6465), 628-631.

• Nedergaard, M., & Goldman, S. A. (2020). Glymphatic failure as a final common pathway to dementia. Science, 370(6512), 50-56.

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Stimulate Your Lymphatic System

Since the lymphatic system lacks a pump it relies on muscular contractions associated with physical activity to keep everything flowing smoothly. This short routine will stimulate lymphatic flow. 

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Fall Asleep Fast

This deep sleep guided meditation by Jason Stephenson is one of many free bedtime tracks available online.