New Theory About the Purpose of Sleep and Why Its So Important to Get Sound Sleep

by Ram

Sleep by Francisco Goya

According to Ayurveda philosophy, sleep is one of three pillars that endow the body with strength, complexion, and healthy growth, which can continue through the full span of life. The Ayurvedic texts also describe the maladies that can result from poor-quality sleep, including but not limited to misery, emaciation, weakness, brain fog, memory loss, and fatigue. It is believed that good quality sleep is essential for the well-being of any individual as the body utilizes the sleep time to repair itself of damage sustained during the waking hours.

In this hypercompetitive world, many of us complain of a lack of good quality sleep. We’re a world of unhealthy sleepers. If one were to compare the world statistics of insomnia and poor quality sleep, it is interesting to note that the numbers are nearly similar throughout the world. Within the USA, 30 percent of us have trouble falling asleep (insomnia) and 50 percent can sleep but have trouble maintaining sound/quality sleep due to tension, work, stress and/or emotional upheaval. 

Nearly 10 million people in the U.S. use prescription sleep aids. Several recent studies have shown that lack of sleep or a discontinuous sleep during the night may be deleterious for the brain, and may trigger dementia and increase the risk of stroke symptoms. For more on sleep and suitable interventions, check our earlier posts on these topics including: sleep and memory by Nina Sleep, Alzheimer's Disease and Yoga and The Importance of Good Sleep and natural interventions for good sleep 5 Tips for Better Sleep. 

The type of sleep and how we are affected by it is of great interest to sleep researchers. Sleep researchers have provided a number of reasons for why we sleep. Sleep helps to maintain a healthy immune system, balance our appetites, makes us less susceptible to degenerative diseases or infections, improves memory, and enhances cognition. Recent research work points to another interesting fact about why we sleep. Published just a week ago, a pair of papers offers evidence for another theory: Ultrastructural evidence for synaptic scaling across the wake/sleep cycle and Homer1a drives homeostatic scaling-down of excitatory synapses during sleep. 

According to these researchers, sleep helps us to forget some of the things we learn each day. Learning requires new neuronal connections or neuronal branching in our brains, which help neurons to communicate with neighboring neurons quickly and efficiently. Furthermore, these new neuronal branches also store firsthand memories of impressions that we draw in each day through our five senses. However, some of this information is redundant and does not require being stored. For example, you do not need to know what clothes you wore to work on a Thursday couple of weeks ago. Similarly, the people you saw at the airport terminal is not a value for the brain. 

In the first study Ultrastructural evidence for synaptic scaling across the wake/sleep cycle scientists from the University of Wisconsin-Madison proposed that neuronal branches grow so wildly during the day with all our experiential learning that our neuronal circuits actually get “noisy” (in neuroscience, “noisy” refers to the constant bombardment of electrical activity in neurons that can be measured by sophisticated machines). These scientists further added that when we sleep soundly, the brain discards all the unnecessary noise and consolidates only the relevant signals. In one experiment, scientists grew neurons in a lab dish and fed the neurons with a drug that stimulates the excess noise (that is, growth of extra neuronal branches). Twenty four hours later, the neurons had pared backed some of the branches. In a follow up experiment, the scientists surveyed brain tissue slices from mice that slept soundly and compared them to tissue slices from mice that were forced to keep awake. The neuronal branches in the mice that slept were much smaller and far less “noisy” compared to neuronal branches from mice that were forced to stay awake.

The second study Homer1a drives homeostatic scaling-down of excitatory synapses during sleep, led by scientists from Johns Hopkins University, explored the same theory with a different set of experiments. In this case, the researchers created a tiny window through which they could peer into mouse brains. They added a chemical that would light up each time a new neuronal branch developed, suggesting a new learning had triggered electrical activity, resulting in a noise. 

Looking through the window, they found that the chemical lit up very few times in mice that were asleep, suggesting that the brain was discarding all the extra branches resulting in reduced noise. This suggested that sleep turned on the pruning machinery to pare back the excess neuronal branches. More importantly, this sleep-induced pruning of neurons helped in consolidating memories. Mice that were not allowed to sleep ended up with less pruning of the branches, more neuronal noise, and fuzzy memories. Interestingly, the pruning machinery was very specific; it did not prune the well-established old neuronal connections. 

To provide an analogy, I am reminded of what the computer folks always advise us when the computer starts functioning erratically. Before thinking of any expensive repairs, the first thing they do is to switch off the computer and reboot it. The reasoning is that the processor discards and clears the hard drive of all of the unnecessary and not-needed information. So the take-home message is that we do not need to harbor all the information that we encounter briefly on a day-day basis, especially the bad, unpleasant, sad, and negative events. 

Every day we encounter brief negative thoughts/experiences —when we typically experience a brief bout of anger—that do not need to be consolidated. For example, while driving you may have encountered someone who speeded wildly and overtook you without signaling, or maybe your waiter took a long time to bring the lunch order and you got delayed for your next important meeting. These situations need not be stored as it is not helpful—it is a noise that we need to erase by sleeping soundly.

If we cannot discard these negative experiences through sound sleep, these disharmonious memories can keep lurking in the brain for a long time, and create the excess noise through the numerous unwanted neuronal branches and erratic electrical activity that will have deleterious effects on the brain. 

Sleep experts are now busy trying to discover medicines that might precisely target the molecules to induce sleep, ensuring that neuronal branches get properly pruned and all the junk information is purged. However, as yogis we know what works better naturally than medicines: a good sleep. Remember, good sleep is essential for a person’s health and wellbeing and if you are experiencing sleep problems, there is quite a price to pay.

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