As good as it feels to get cozy under blankets and sink into your pillow at night, sleep isn’t a luxury. It's a necessity.
In a recent animal study, researchers at the University of Rochester’s Medical Center showed that sleep might allow us to clear toxic, metabolic waste from the brain. (1) In other words, sleep is an essential part of detoxification and renewal.
While the rest of the body uses blood and lymphatic fluid to cart away toxic waste from cells, the brain isn’t equipped with this lymphatic plumbing. Instead, the brain relies on cerebrospinal fluid, which flows through the brain and spinal cord.
Cerebrospinal fluid and the brain’s immune system make up the glymphatic system. This system filters out waste and harmful metabolites that play a role in disorders that affect the brain, like dementia and Alzheimer’s disease.
Using mice, researchers at the University of Rochester tracked the flow of fluid between brain cells and through the central nervous system. They found that brain cells contract. They also found that the space between cells increased from 14% of brain volume to 23%.
This translates into a 60% increase in space between cells. During sleep, cells are bathed in larger amounts of cleansing fluid than during waking hours.
Catching some zzz's means more than getting your beauty rest. Even mild sleep deprivation has been linked to anxiety and difficulty processing emotions.
Researchers also injected mice with amyloid protein—the same protein that builds up like plaque in the brain and is associated with Alzheimer’s disease. It turns out that a sleeping brain is more adept at clearing amyloid plaque than a brain that is awake.
"The brain only has limited energy at its disposal, and it appears that it must choose between two different functional states—awake and aware or asleep and cleaning up," says Dr. Maiken Nedergaard, co-director of the University of Rochester Medical Center and lead author of the study. "You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time."
Interrupted Sleep and Brain Toxicity
When the brain is not able to clear out waste, it accumulates in the brain like dust on a shelf. The problem is that this waste is toxic, and it can instigate mechanisms like inflammation and cell death.
Signs of toxic waste buildup in the brain include:
- Seizures (2)
- Manic highs and lows (3)
- Depression (4)
- Dementia (5)
Neuroscientists have also found that even mild sleep deprivation can fire up anxiety and distort the brain’s ability to process emotions. (6)
While previous studies have shown a relationship between mental disorders and sleep deprivation, only recently have scientists teased out a causal link between sleep loss and mood disorders, like anxiety. Unfortunately, those who are more anxious also tend to have a low threshold for missed hours of sleep.
The Problem with Blue Light
Within the brain, there is an internal “clock” that regulates the flow of specific hormones. This internal clock receives direct input from the eyes and, in particular, in response to light.
Researchers at Johns Hopkins University suggest that aberrant light—such as the light from television, in a grocery store, or even a nightlight—is enough to generate depression and changes in mood. (7) On studies in mice, they found that even with regular sleep cycles and a normal circadian rhythm, aberrant light triggered the production of more stress hormones, as well as signs of depression and difficultly learning.
Still other studies show that blue light is especially problematic. Many electronic devices emit blue light.
These include devices that many of us look at before going to bed and upon waking:
- Computer screens
In the brain, blue light mimics daylight. (8) The human body is hardwired to take cues from the environment—for better or worse. In this case, artificial blue light places unnecessary stress on the body’s sleep and wake cycles, never allowing us to have a proper night’s sleep.
5 Suggestions for a Good Night's Sleep
Sleep ensures the regeneration of new tissue and cells. It literally creates the space necessary for healing, helping the body to defend itself against neurodegenerative disease and long-term mood disorders.
A good night’s sleep is essential for a healthy brain.
For your last meal of the day, we suggest combining Body Ecology grain-like seeds (such as millet, quinoa, buckwheat, or amaranth) with non-starchy vegetables and ocean vegetables. Complex carbohydrates, like those found in grain-like seeds, have a calming effect on the body and stimulate the production of soothing neurotransmitters, which can help ease you into slumber.
Ending the day with a meal that contains complex carbohydrates also safeguards against dramatic drops in blood sugar. Low blood sugar during sleep is a surefire way to release regulating stress hormones that wake you up in the middle of the night.
To make the most out of every night’s rest, we also suggest that you:
- Avoid stimulants after noon, such as coffee, stimulating tea, and chocolate.
- End electronic communication, like email and texting, around sunset.
- Turn off the television at least 2–3 hours before bedtime.
- Unwind from the day with dim incandescent light or candlelight.
- Consider installing bedroom curtains that block out outside light.
What To Remember Most About This Article:
Sleep may feel like a luxury after a busy week balancing work and home life, but it's also a necessity to clear toxic waste from your brain. Sleep supports brain detoxification and renewal. Brain cells contract and are bathed in cleansing fluid as you sleep.
Toxic waste can quickly accumulate in the brain if it isn't flushed out regularly during sleep. Symptoms like migraines, seizures, depression, anxiety, and even autism may be the result of brain toxicity.
In your brain, you'll also find an internal clock that regulates hormones and responds to light. Blue light from electronic devices may be especially problematic since it mimics daylight. This artificial light can throw your sleep cycle out of whack and affect a sound night of rest.
Support your brain health with good sleep habits, like:
- Avoiding stimulants after noon.
- Ending electronic communication at sunset.
- Turning off the TV 2-3 hours before bed.
- Unwinding in the evening by candlelight or with dim incandescent light.
- Installing blackout curtains in the bedroom to block out light.
- Xie, L., Kang, H., Xu, Q., Chen, M. J., Liao, Y., Thiyagarajan, M., ... & Nedergaard, M. (2013). Sleep Drives Metabolite Clearance from the Adult Brain. Science, 342(6156), 373-377.
- Gale, K. (2004). Epilepsy and Seizures: Excitotoxicity or Excitotrophicity?. In Excitotoxicity in Neurological Diseases (pp. 137-170). Springer US.
- Rao, J. S., Harry, G. J., Rapoport, S. I., & Kim, H. W. (2009). Increased excitotoxicity and neuroinflammatory markers in postmortem frontal cortex from bipolar disorder patients. Molecular psychiatry, 15(4), 384-392.
- Weber, M., Webb, C. A., Deldonno, S. R., Kipman, M., Schwab, Z. J., Weiner, M. R., & Killgore, W. D. (2013). Habitual ‘sleep credit’is associated with greater grey matter volume of the medial prefrontal cortex, higher emotional intelligence and better mental health. Journal of sleep research.
- Hynd, M. R., Scott, H. L., & Dodd, P. R. (2004). Glutamate-mediated excitotoxicity and neurodegeneration in Alzheimer’s disease. Neurochemistry international, 45(5), 583-595.
- Goldstein, A. N., Greer, S. M., Saletin, J. M., Harvey, A. G., Nitschke, J. B., & Walker, M. P. (2013). Tired and Apprehensive: Anxiety Amplifies the Impact of Sleep Loss on Aversive Brain Anticipation. The Journal of Neuroscience, 33(26), 10607-10615.
- LeGates, T. A., Altimus, C. M., Wang, H., Lee, H. K., Yang, S., Zhao, H., ... & Hattar, S. (2012). Aberrant light directly impairs mood and learning through melanopsin-expressing neurons. Nature, 491(7425), 594-598.
- Lockley, S. W., Brainard, G. C., & Czeisler, C. A. (2003). High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. J Clin Endocrinol Metab, 88(9), 4502-4505.