"To sleep, perchance to Dream...." —William Shakespeare

When Hamlet utters this line in Shakespeare's play, he is contemplating suicide after learning that his uncle has killed his father, the King, and married Hamlet's mother. For Hamlet, death is initially seen as an escape from his torment, until Hamlet wonders whether we dream in death and whether those dreams would bring unending anguish.

Tough times for Hamlet. But Hamlet is not the only literary character whose life is affected by the nature of sleep. Speculative fiction contains other examples in which sleep plays a prominent part in the story. Here are some of them....

Nod by Adrian Barnes

Scientists often extol the virtues of sleep on the human mind and body. In the atmospheric novel Nod, author Adrian Barnes poses the opposite side of that coin by exploring a condition wherein the majority of the world's population suffers from extreme sleep deprivation. There seems to be no cure for the chronic condition, but the effects quickly make themselves evident: psychosis sets in after six days...and death will result after four weeks. During this time, panic escalates in a society where the eventual result becomes clear: a new world order is emerging where those fortunate few (about one in10,000) who are unaffected by this bizarre condition are the ones who will be in control. This calamitous changing of the guard is witnessed through the eyes of a writer who can still sleep while his unfortunate partner deteriorates before his eyes.

It's worth noting that Nod was a finalist for the prestigious Arthur C. Clarke Award. It has also been optioned for film and television.

Black Moon by Kenneth Calhoun

Insomnia plays a big part in Kenneth Calhoun's Black Moon as well. Here, insomnia has reached epidemic proportions and the sleepless roam the streets day and night looking for some escape. But their condition is sadly not curable. Money can't buy it and drugs and can't fix it. As tension escalates in an increasingly desperate world, the sleepless attack those who can still sleep, and survival becomes more difficult. It is in this harrowing apocalyptic landscape that the main characters find themselves searching for an alternative. There's Lila, a sleeper who is sent away by her sleepless parents; Biggs, a sleeper who pretends he can't sleep just so he can safely search for his sleepless wife, Carolyn, who has been missing since the epidemic hit; Chase and Jordan, two friends who choose to raid drug stores in the misguided hope of finding some much-needed rest; and Felicia, who goes into hiding with a group of doctors who are desperately looking for a cure to the insomnia epidemic.

Sleepless by Charlie Huston

The world of Charlie Huston's Sleepless is insomnia-plagued as well, but at least there's a cure: Dreamer is a drug that can give the sleepless the rest they so desperately need. Parker Haas is a Los Angeles police officer who is devoted to making the city a better place. That includes investigating the black market supply of Dreamer, which he does by going undercover. He learns that there is a worldwide conspiracy that is artificially limiting the supply of Dreamer, lining the pockets of a select few while the world deteriorates. Parker is faced with another moral dilemma as well when he must decide between justice and procuring the drug that could cure his sleepless wife and infant daughter.

The Sleepless Trilogy by Nancy Kress

Nancy Kress' Sleepless trilogy began as a superb short story called "Beggars in Spain." Eventually that story was expanded into the equally excellent novel Beggars in Spain. Instead on seeing insomnia as a condition to be cured, Beggars in Spain posits a scenario in which sleeplessness is seen as an asset. In an effort to change lives into being more productive (as in: not requiring sleep), scientists develop a way to genetically engineer "designer babies" that never need to sleep. Leisha Camden is one of this new generation of Sleepless humans. However, a separation eventually develops between normal humans and those who are genetically modified. Th e Sleepless become outcasts, shunned by a society who fears them. Eventually, the Sleepless carry on their genetic research on a space habitat, creating a new generation of Sleepless with even more superhuman abilities and preparing for an eventual war with Earth. Meanwhile Leisha, who rejects the separation, works on Earth to help all humankind.

In the sequel, Beggars and Choosers, the split between natural humans and the handsome and intellectually superior gene-modified humans widens. The Sleepless occasionally reveal amazing new technological marvels for all humans to use, yet they seem to have their own agenda for humanity.

In the final book in the trilogy, Beggar's Ride, Kress' depiction of evolutionary forces comes to a close as two generations of genetically modified humans—the first generation Sleepless and the second generation SuperSleepless—are in conflict with each other and maneuver to become the dominant sub-species. The natural humans, meanwhile—by now affected by economic forces that have created a division of their own between rich and poor—are effectively helpless to stop it.

John DeNardo is the editor of SF Signal, the Hugo Award-winning group science-fiction and fantasy blog featuring news, reviews and interviews. You can follow him on Twitter as @sfsignal.