Suspended animation is the slowing or stopping of life processes by exogenous or endogenous means without termination. Breathing, heartbeat, and other involuntary functions may still occur, but they can only be detected by artificial means.
Since the 1970s, induced hypothermia has been performed for some open-heart surgeries as an alternative to heart-lung machines. Hypothermia, however, provides only a limited amount of time in which to operate and there is a risk of tissue and brain damage for prolonged periods.
Sleep is a naturally recurring state of mind characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but is more easily reversed than the state of hibernation or of being comatose. Mammalian sleep occurs in repeating periods, in which the body alternates between two highly distinct modes known as non-REM and REM sleep. REM stands for “rapid eye movement” but involves many other aspects including virtual paralysis of the body.
During sleep, most systems in an animal are in an anabolic state, building up the immune, nervous, skeletal, and muscular systems. However, sleep patterns vary widely among animals and among different individual humans.
Sleep seems to assist animals with improvements in the body and mind. A well-known feature of sleep in humans is the dream, which resembles waking life while in progress, but which usually, can later be distinguished as fantasy. Humans may suffer from a number of sleep disorders. These include dyssomnias (such as insomnia, hypersomnia, and sleep apnea), parasomnias (such as sleepwalking and REM behavior disorder), bruxism, and the circadian rhythm sleep disorders.
Dreams are successions of images, ideas, emotions, and sensations that occur usually involuntarily in the mind during certain stages of sleep. The content and purpose of dreams are not definitively understood, though they have been a topic of scientific speculation, as well as a subject of philosophical and religious interest, throughout recorded history. The scientific study of dreams is called oneirology.
Dreams mainly occur in the rapid-eye movement (REM) stage of sleep—when brain activity is high and resembles that of being awake. Continuous movements of the eyes reveal REM sleep. At times, dreams may occur during other stages of sleep. However, these dreams tend to be much less vivid or memorable.
The length of a dream can vary; they may last for a few seconds, or approximately 20–30 minutes. People are more likely to remember the dream if they are awakened during the REM phase. The average person has three to five dreams per night, and some may have up to seven; however, most dreams are immediately or quickly forgotten. Dreams tend to last longer as the night progresses. During a full eight-hour night sleep, most dreams occur in the typical two hours of REM.
Dreams have been seen as a connection to the unconscious mind. They range from normal and ordinary to overly surreal and bizarre. Dreams can have varying natures, such as being frightening, exciting, magical, melancholic, adventurous, or sexual. The events in dreams are generally outside the control of the dreamer, with the exception of lucid dreaming, where the dreamer is self-aware. Dreams can at times make a creative thought occur to the person or give a sense of inspiration.
Opinions about the meaning of dreams have varied and shifted through time and culture. The earliest recorded dreams were acquired from materials dating back approximately 5000 years, in Mesopotamia, where they were documented on clay tablets. In the Greek and Roman periods, the people believed that dreams were direct messages from one and/or multiple deities, from deceased persons, and that they predicted the future. Some cultures practiced dream incubation with the intention of cultivating dreams that are of prophecy.
Sigmund Freud, who developed the discipline of psychoanalysis, wrote extensively about dream theories and their interpretations in the early 1900s. He explained dreams as manifestations of our deepest desires and anxieties, often relating to repressed childhood memories or obsessions.
A nightmare is an unpleasant dream that can cause a strong emotional response from the mind, typically fear or horror but also despair, anxiety and great sadness. The dream may contain situations of danger, discomfort, and psychological or physical terror. Sufferers often awaken in a state of distress and may be unable to return to sleep for a prolonged period.
Nightmares can have physical causes such as sleeping in an uncomfortable or awkward position, having a fever, or psychological causes such as stress, anxiety, and as a side effect of various drugs. Eating before going to sleep, which triggers an increase in the body's metabolism and brain activity, is a potential stimulus for nightmares. Recurrent nightmares may require medical help, as they can interfere with sleeping patterns and cause insomnia.
It seems so simple. The sky gets dark so you put on your jammies and crawl under the covers and close your eyes only to be in some sort of suspended animation until the sun comes up. You wake up, stretch your arms, yawn in a big breath of air, and with your body and mind refreshed, and start a new day. It seems so simple.
Except when it is not that easy.
Sure you know people who can sit down in a chair and fall asleep. You can watch your pets for no reason at all, just lie down and fall asleep. Some can sleep from mental or physical exhaustion and some need aids to conk out. Some can sleep on the ground while others can’t sleep in the most accommodating mattress.
Some think they don’t need much sleep but when the body is tired, it will win. It is our recharge time.
Except for those nights (or days) when the body can’t find a comfortable spot and the mind won’t shut off. The thoughts range from what needs to be done the next day or is the backdoor locked. A Rolodex of ideas, thoughts, wishes and remembrances will flood the mind nonstop. They don’t have to be in sequence or any pattern and can jump from the present to the past.
On those nights, perhaps a stiff drink or two will persuade your mind to shut up. A different pattern of reading or watching television or looking at the stars, but upon return to the bed, it starts all over again.
Sleep, you elusive mistress, will you visit me tonight?