BY SHERIKA TENAYA
It’s no secret that sleep is important. And yet, these days, it feels as though we need to strategize our sleep. With the constant bombardment of electric lights, televisions, computers, tablets and smartphones - it comes as no surprise that the average American today sleeps less than seven hours a night - which is both the minimum recommended number of hours and is also two hours less than people slept a century ago.
That’s 80 million American adults that are chronically sleep deprived and we know the results are dire: hurting our immune system, injury recovery time and mental health.
According to Michael Finkel, the amazing author of this supremely well-written National Geographic article on sleep science writes, “Anyone who regularly sleeps less than six hours a night has an elevated risk of depression, psychosis, and stroke...underslept people are more irritable, moody, and irrational...and lack of sleep is also directly tied to obesity.”
And sleep, we’re beginning to understand, is one of the greatest contributors to a long-lived, healthy memory.
Finkel beautifully describes the healing process that happens on a nightly basis in the brain. A process that wards off beta-amyloid, a substance highly implicated in the development of Alzheimer’s disease. He writes, “While we’re awake, our neurons are packed tightly together, but when we’re asleep, some brain cells deflate by 60 percent widening the spaces between them. These intercellular spaces are dumping grounds for the cells’ metabolic waste...and only during sleep can spinal fluid slosh like detergent through these broader hallways of our brain, washing beta-amyloid away.”
Sleep is so integral to memory preservation that Finkel warns how it might impact lasting trauma imprinting, “sleeping soon after a major event, before some of the ordeal is mentally resolved, is more likely to turn the experience into long-term memories.”
So what, exactly, happens during the sleep process that makes it so powerfully healing?
It was this pondering that inspired me so profoundly when I read Finkel’s article in NatGeo. His way of describing sleep, somewhat reminiscent of the artistry found in Dante’s Descent Into Hell, captures the imagination as well as the full impact and power of the sleep process:
Yet it all begins with stage one - the lightest stage of sleep - that lasts all of five minutes in which neurons begin to fire evenly and rhythmically together.
Stage two, which can last up to 50 minutes, is characterized by the appearance of spindles, fizzing bursts of electrical activity that continuously zap the cerebral cortex, the wrinkly gray exterior part of the brain from which originates language and self-awareness. “These half-second bursts,” Finkel writes, “indicate that we’ve entered stage 2...it’s theorized [they] stimulate the cortex in such a way as to preserve recently acquired information. The waking brain is optimized for collecting external stimuli, the sleeping brain for consolidating the information that’s been collected.”
Spindle frequency and force are considered by some experts to be good indicators of general intelligence and associated with more efficient learning of new tasks.
Spindle firings slowly diminish and, as our heart rate slows and our core temperature drops, we ease into stages three and four. This is the time of deep sleep, with long, depthful delta waves being predominant in stage 4, which can only last for as long as thirty minutes before the brain wakes itself up.
This is the stage of sleep in which the major healing processes of the body take place, with the increased production of growth hormone, a powerfully regenerative substance that rebuilds the tissues of both body and brain, paired with complete and utter muscle relaxation.
“Stage 4 waves are similar to patterns produced by coma patients.” Finkel explains. “We do not dream during stage 4; we may not even be able to feel pain.”
Perhaps this is why Edgar Allen Poe is famously quoted as calling sleep “little slices of death”. He’s not far off the mark, according to Michael Perlis, the director of Behavioral Sleep Medicine program at the University of Pennsylvania, who was quoted in Finkel’s article as saying, “You’re talking about a level of brain deactivation that is really rather intense. Stage 4 sleep is not far removed from coma or brain death.”
After Stage 4 is when we slip into the infamous REM (rapid eye movement) state, which comprises about one-fifth of total rest time in adults. At this stage of the game, management of our brain is transferred away from the logic centers and given over to the impulse-control region, yet the brain is fully activated - consuming as much energy as when we’re awake.
Our internal temperature drops to its lowest capacity even as our heart rate increases and the characteristic eye darting ensues. Not only are our inner ears activated at this point, but also the motion centers of the brain fire off in an attempt to create movement, which is why we dream of falling or flying, but this attempted motion is thwarted by another part of the brain that deactivates our motor-neuron gate. Our sexual organs get flushed and full, and we dream - not just momentary blips as we might imagine - but spanning over two hours per night, generally speaking.
Surprising, isn’t it? I, for one, can barely remember a few vaguely sparse snapshots of my dreams most nights...but before you or I start feeling perturbed by the fact that so much of our dream world is lost to the ethers, Finkel assures, “lack of dream recollection is actually an indication of a healthy sleeper.” #winning
Did you know that you dream in color? “Unless we’ve been blind from birth,” Finkel remarks. “In which case dreams do not have visual imagery but remain emotionally intense.”
Sleep, at its most ideal, consists of a sinking down from the non-REM stages of 1 through 4. There’s a momentary return to wakefulness, followed by a 5 - 20 minute REM session. Each cycle after the first, REM time doubles.
Interestingly enough, Finkel says that sleep scientists suspect that specific sequences of non-REM and REM sleep may, in a way, promote physical and mental recuperation.
So now we have a little clearer insight into where the phrase, “I’ll sleep on it” comes from. Sleep is absolutely vital to our brain and our bodies, with many different moving parts that all work together to create a symbiosis of healthful healing, memory imprinting and rejuvenation.