Scientific mysteries

Humans have made a staggering amount of scientific and technological progress over the past century. We’ve created technology that has transformed our society; scientific advances have helped us answer fundamental questions about who we are and the world that we inhabit. And, yet, mysteries persist.

Why are we compelled to sleep every night? Why are we still not able to “see” dark matter? And where the heck are all the aliens?

People have debated questions like these for decades — sometimes centuries. Fortunately, our unfaltering will to uncover the world’s mysteries has brought us closer to some answers than ever before. Here are six mysteries that still keep scientists up at night, and how close they are to solving them.

Why Do We Need Sleep?

Why do we need sleep? This may seem like a straightforward question, but the answer is far more complex than you might think. There have been countless attempts to find a definitive reason as to why humans need to sleep every night, but scientists are still unable to offer a single, definitive answer.

Findings in sleep science have shed some light on the intricacies of sleep stages and brain activity, but ultimately, they have merely offered pieces to an ever-growing, incomplete puzzle. It doesn’t help that we don’t have much to compare ourselves to — as sleeping patterns and brain activity in other animals often deviate significantly from those of humans, further mystifying our understanding of sleep.

Jerry Siegel, a psychiatry professor at UCLA’s Semel Institute of Neuroscience and Human Behavior, has been studying the sleeping habits of animals to understand why humans need to enter a hibernation-like state every night.

“Our understanding and orientation [of sleep] is different than in any other animal because most of us would like to stay awake 24 hours a day. But in the natural world, animals that use a lot of energy are not going to survive,” Siegel tells Futurism. Nature values inactivity — for instance, winter hibernation allows certain animals to recover and store energy when it is not needed. “Across species, energy savings is the main evolutionary impulse for sleep,” Siegel explains. African elephants, for example, only sleep for two hours a day in the wild, likely because they need the rest of that time to feed in order to give their large bodies enough energy to function.

The energy saving theory is one of several that scientists use to explain why we sleep. As scientists have created tools that can track brain activity during the act of sleep, they have come closer to finishing the puzzle and uncovering all of sleep’s mysteries.

For example, the brain has mechanisms in place allowing it to purge itself of unnecessary information during sleep. “Sleep is the price we pay for learning,” Giulio Tononi, a psychiatry professor at the University of Wisconsin-Madison tells New Scientist. Tononi and his team conducted experiments on sleeping mice and found that, after sleep, synapses were significantly smaller than those before sleep.

Tononi’s team concluded that the brain needs to allow this activity to diminish in order to solidify information it gathered while it was awake. The brain is bombarded with information during the day, and it reinforces it with strong neural connections. To mix the new information in with all of the existing information, those connections need to weaken to “absorb” it. In other words, sleep allows the brain to make new information pliable enough to fit in with all of the old.

While this theory elegantly describes the brain’s process of making new information stick during sleep, Tononi and other neuroscientists have yet to prove that sleep is actually required for this to happen.

To fully understand sleep, sleep scientists need a better sense of the neurobiological processes of the brain during both wake and sleep cycles. For instance, how come some of us are able to sleep through extremely noisy environments, and some of us can’t? Once we are able to measure exactly how awake or asleep the human brain is, it will bring us even further to knowing all there is to know about sleep.

But one thing has remained clear as ever: Without sleep, we are far worse off. “We know that, if you are sleep-deprived, you have lapses in attention that are actually correlated with intrusions in sleep,” Siegel says. Not getting enough sleep has a direct affect on how much attention you can pay to the world around you. “Certainly when you are driving, losing alertness just for two seconds can be lethal.