he tuatara, a primitive lizardlike reptile found on the islands of the South Pacific, has three eyes. The third eye, located in the middle of the animal's forehead, doesn't "see" in the conscious sense of the word—it's a single-pixel sensor, like the photocell that turns your bathroom nightlight on and off. It doesn't produce images, or probably even sensory impressions this cold-blooded critter is aware of. But like a photocell, it does use brightness to turn a circuit on and off. In the tuatara's case, though, the switch doesn't control a light bulb, but a hormone duct called the pineal gland, which waits for nightfall and then floods the brain with melatonin—the chemical messenger of sleep.
Ah, sleep. We hate it, we love it, we can't live without it. Not for more than about 11 days, anyway, and not without potentially crippling side effects like irritability, slowed reactions, impaired judgment, hallucinations and sometimes actual tissue damage. And while human sleep patterns are more complex than those of the tuatara, we too have a pineal gland—a vestigial third eye buried deep in the center of the brain. Creeeeepy.
Anyway, research has shown that like many things in the body and mind, sleep is a delicate balancing act between the need to rest and regenerate and stay out of trouble, and the need to get up and make a living in a generally unforgiving world. Sleep and alertness exert a constant neural tug of war over our lives, and in healthy people the urge to sleep never quite goes away. It's lowest in the morning and highest at night, and it also shows a smaller peak in midafternoon—siesta time in the Spanish-speaking world, or tea time for Anglos. It also plummets when we're busy or afraid, and rises up with a vengeance when we're bored, which is one reason science columnists rely on humor to keep the audience entertained. Now quit yawning or I'll make a loud noise!
To (not) sleep, perchance to (not) dream
Thing is, mammals and sleep have gotten along fine for millions of years. But how could nature have anticipated our modern world, with its artificial light and even more artificial darkness, its bizarre demands of work and driving, its dependence on calendars and schedules with only tenuous links to the rising and setting of the sun? It's no wonder that sleep disorders affect up to 40 percent of the U.S. population, and ill-timed drowsiness has been implicated in at least 15 percent of fatal traffic accidents overall and 40 percent of heavy truck accidents.
Since the domestication of the tea plant around 2700 B.C., and especially the discovery of coffee in 850 A.D., humans have tried to wrest control of the sleep cycle from our primitive neural wiring, through the sledgehammer-crude application of stimulant drugs. Unfortunately, while this strengthens the alertness signals in our brains, it has no actual effect on our need to sleep. As we stave off fair Morpheus, hour upon hour, day upon day, our cumulative "sleep debt" increases, and the side effects pile up inexorably.
But will this always be the case? No matter how complex it may seem, the brain is still a chemical-electrical machine, and each of its operating modes has a unique chemical fingerprint. Can it be fooled? Can a counterfeit of well-restedness be injected into us, tricking the brain into feeling the refreshment of a nap or a good night's sleep? The answer appears to be yes.
The prescription drug Provigil, developed to combat narcolepsy and other sleepiness-related ailments, specifically targets the prefrontal cortex—the center of attention and alertness. In clinical trials, it keeps people more awake and more alert than even high doses of caffeine. Moreover, it does this with virtually no side effects, no jitter or euphoria, even when used for 2 or 3 days at a time. And when the subjects finally sleep, they don't seem to have any debt to pay off. As far as their brains are concerned, they're all caught up.
Right now Provigil is intended only to treat serious disorders, but it's likely to be approved soon for minor ones like jet lag and "shift work sleep disorder." And from there it's a small step to prescribe it for general anti-sleepiness use by truck drivers, police, soldiers and the rest of us. And even better drugs may be in the development pipeline, to keep us even more awake for even longer. I can hardly wait.
The big sleep may get a little smaller
Of course, sleep plays an important role in memory and cognition, as well as immune function and a bunch of other stuff. The long-term abuse of anti-sleep drugs will have all kinds of unforeseen and often unpleasant consequences. Imagine a nation of accidental zombies. But studies have also shown, for example, that healthy people's memories can be improved by drugs like donepezil—intended for Alzheimer's disease and other forms of senility—while the immune system can be revved up by signaling molecules like interferon and by DNA strands called "CpG sequences." With multidrug cocktails, we may find ways to play down even the worst side effects of sleep deprivation.
So if you thought the '90s were a go-go time of round-the-clock action, my guess is that you ain't seen nothing yet. We may soon be entering a time when regular sleep on a regular schedule is genuinely optional, and perhaps even socially discouraged. This could easily turn into a strange new form of tyranny, but even so it will be a boom time for nightclubs, convenience stores and 24/7 gymnasiums.
Alas, there are deeper, nastier forms of sleep which even Provigil can't touch. Shock, for example, is the loss of function which occurs after a sudden drop in blood pressure. Its symptoms include weak pulse, pale sweaty skin, a lack of blood flow to the extremities and loss of consciousness or reduced cognitive function. This response is intended to protect vital organs against blood loss and other trauma, though in severe cases the effect can be fatal. But researchers on Long Island are monkeying with a "neural tourniquet" that stimulates the vagus nerve, which controls—among many other things—the heart. The idea is to speed up that muscle, reducing the symptoms of shock and keeping the blood pressure up, so the brain and body can keep working even in the face of accident, injury or war wounds.
And the party doesn't have to stop there. What about that ultimate drowsiness, the nap that never ends, the Big Sleep? What about death? There's no escaping the reaper (see "So You Want to Live Forever," December 2002), but the physiological mechanisms of death are well understood, and some of them may be amenable to trickery as well. How many people die each year on the way to the hospital? If death, like sleep, could be held at bay until we're ready, it would revolutionize emergency medicine to its very core.
When the heart stops beating, body tissues are deprived of oxygen, and within 5 to 10 minutes the mitochondria in their cells stop producing the energy-rich molecule ATP, leading to a failure of the ion pumps that regulate the levels of sodium and potassium in the cell. Without that control, the cells begin to swell, pinching off blood vessels and making it impossible to restore the flow of oxygen. At this point, although the brain and body may be largely intact, we can no longer reverse the chemical processes of their decline. We throw in the towel, declare death and ship the body to the morgue. Entropy wins.
But cooling the body can slow this process dramatically; at room temperature it takes 2.5 times longer than at normal body temperature. And by flooding the tissues with oxygen-carrying molecules like polymerized hemoglobin (see "Blood's Brothers," October 2001), we may stretch it out even further than that. Before the end of the next decade, reviving a patient after 30 minutes of (supervised) cardiac arrest may be a routine procedure.
And with a bit of Provigil and donepezil, some CpG sequences and a nice nutritious meal, the patient could be back on the street and pulling all-nighters in no time. Let's just save a bit of caffeine, too, for old times' sake.
Wil McCarthy is a rocket guidance engineer, robot designer, science-fiction author and occasional aquanaut. He has contributed to three interplanetary spacecraft, five communication and weather satellites, a line of landmine-clearing robots and some other "really cool stuff" he can't tell us about. His short writings have graced the pages of Analog, Asimov's, Wired, Nature and other major publications, and his book-length works include the New York Times notable Bloom, The Collapsium and most recently The Wellstone and a related nonfiction book, Hacking Matter.
