In 1965, 17-year-old high school student, Randy Gardner stayed awake for 264 hours. That's 11 days to see how he'd cope without sleep. On the second day, his eyes stopped focusing. Next, he lost the ability to identify objects by touch. By day three, Gardner was moody and uncoordinated.
At the end of the experiment, he was struggling to concentrate, had trouble with short-term memory, became paranoid, and started hallucinating. Although Gardner recovered without long-term psychological or physical damage, for others, losing shut-eye can result inhormonal imbalance, illness, and, in extreme cases, death.
We're only beginning to understand why we sleep to begin with, but we do know it's essential. Adults need seven to eight hours of sleep a night, and adolescents need about ten. We grow sleepy due to signals from our body telling our brain we are tired, and signals from the environment telling us it's dark outside.
The rise in sleep-inducing chemicals, like adenosine and melatonin, send us into a light doze that grows deeper, making our breathing and heart rate slow down and our muscles relax. This non-REM sleep is when DNA is repaired and our bodies replenish themselves for the day ahead.
In the United States, it's estimated that 30% of adults and 66% of adolescents are regularly sleep-deprived. This isn't just a minor inconvenience. Staying awake can cause serious bodily harm. When we lose sleep, learning, memory, mood, and reaction time are affected. Sleeplessness may also cause inflammation, halluciations, high blood pressure, and it's even been linked to diabetes and obesity.
In 2014, a devoted soccer fan died after staying awake for 48 hours to watch the World Cup. While his untimely death was due to a stroke, studies show that chronically sleeping fewer than six hours a night increases stroke risk by four and half times compared to those getting a consistent seven to eight hours of shuteye.
For a handful of people on the planet who carry a rare inherited genetic mutation, sleeplessness is a daily reality. This condition, known as Fatal Familial Insomnia, places the body in a nightmarish state of wakefulness, forbidding it from entering the sanctuary of sleep. Within months or years, this progressively worsening condition leads to dementia and death.
How can sleep deprivation cause such immense suffering? Scientists think the answer lies with the accumulation of waste prducts in the brain.
During our waking hours, our cells are busy using up our day's energy sources, which get broken down into various by products, including adenosine. As adenosine builds up, it increases the urge to sleep, also known as sleep pressure.
In fact, caffeine works by blocking adenosine's receptor pathways. Other waste products also build up in the brain, and if they're not cleared away, they collectively overload the brain and are thought to lead to the many negative symptoms of sleep deprivation.
So, what's happening in our brain when we sleep to prevent this? Scientists found something called the glymphatic system, a clean-up mechanism that removes this buildup and is much more active when we're asleep. It works by using cerebrospinal fluid to flush away toxicbyproducts that accumulate between cells.
那我们睡觉的时候大脑是如何防止这些发生的呢？科学家们发现了一种叫glymphatic system 的脑部淋巴系统，一种能清除这些积聚物的清扫系统。当我们睡觉的时候这个系统更加活跃，它利用脑脊液来清除在细胞之间的有毒物质。
Lymphatic vessels, which serve as pathways for immune cells, have recently been discovered in the brain, and they may also play a role in clearing out the brain's daily waste products.
While scientists continue exploring the restorative mechanisms behind sleep, we can be sure that slipping into slumber is a necessity if we want to maintain our health and our sanity.