Alpha Waves (8-12 cycles per second) - These are found mainly in adults who are awake, have their eyes shut, and are deeply relaxed. They facilitate inspiration, fast assimilation of facts, and heightened memory. Less than half and epoch (about 30 seconds) of continuous alpha rhythm indicates sleep onset.
Apnea - This is a relatively rare but serious sleep disorder. In sleep apnea, the individual stops breathing while asleep. There are two main reasons for apnea attacks. One reason is that the brain fails to send a "breathe" signal to the diaphragm and other breathing muscles, thus causing breathing to stop. The other reason is that muscles at the top of the throat become too relaxed, allowing the windpipe to partially close, thereby forcing the breathing muscles to pull harder on incoming air, which causes the airway to completely collapse. During an apnea, the oxygen level of the blood drops dramatically, leading to the secretion of emergency hormones. This reaction causes the sleeper to awaken in order to begin breathing again. Apnea, in most cases, has been found to be an inherited trait.
Beta Waves (13 - 25 cycles per second) - These are found mainly in adults who are awake, alert, whose eyes are open and who may be concentrating on some task or other activity. They are most reliably recorded from the front and middle of the scalp, and are related to activity in the sensory and motor cortex.
Cognition - An individual's thoughts, knowledge, interpretations, understandings, ideas, awareness, perception, reasoning, and judgement.
Consciousness - We are conscious when we are aware of external events, reflect on past experiences, engage in problem solving, are selective in attending to some stimuli rather than others, and deliberately choose and action in response to environmental conditions and personal goals.
Delta Waves ( 0.5 - 3 cycles per second) - These are dominant waves of deep, dreamless sleep, which take place in stages three and four of sleep.
Dream Initiated Lucid Dream (DILD) - This term describes a lucid dream in which the dreamer becomes lucid while involved in an ongoing dream. Usually this occurs when you notice that you are dreaming and something is definitely not normal.
Electroencephalogram (EEG) - A record of brain activity obtained by attaching electrodes to the scalp and amplifying the spontaneous electrical activity of the brain. The results are recorded on a polygraph machine.
Electromyogram (EMG) - This is a mechanism used to measure muscle activity. It is usually attached to a subject's chin in sleep and dream experiments.
Electrooculogram (EOG) - This device measure the movement of the eyelids during dreaming periods.
Enuresis - This is an occurrence common in children and is better known as bed wetting.
False Awakening - A false awakening occurs in a dream when you think you have just woken up from a dream, but really you have not. An example of a false awakening would be that in a dream you find a bag of money, then you wake up and find the bag of money beside your bed, and then you really wake up to find that the money bag is gone. This can happen more than one time within a dream and tends to make you quite confused.
Insomnia - This is one of the more common sleeping disorders where a person is either unable or afraid to go to sleep. This disorder is also sometimes caused by sickness of disease.
Light Initiated Lucid Dream (LILD) - This type of lucid dream is usually initiated by some form of electronic device that emits light when it detect a person has reached REM sleep. It is used to help a person realize that they have begun dreaming, thus bringing them into the lucid dreaming state.
Lucid Dream - A dream in which the dreamer becomes aware that they are dreaming, and can carry on the dream with unbroken awareness. Dreaming in this state is a skill which can be learned. Lucid dreams, like all dreams, usually occur during REM sleep. Most of us have had a lucid dream during our life, whether we remember it from childhood (a high-level lucid dream) or from two days ago (a low-level lucid dream).
Myoclonic Jerk - A sudden jerk that occurs while you are falling asleep. Sometimes these jerks are so sudden that they wake you from your sleep. It usually occurs between stage one and stage two of sleep. It is actually caused by your brain and thinking that your body is falling into a coma, sends an electric charge throughout your body causing it to convulse.
Narcolepsy - This is a severe sleeping disorder. A person who has narcolepsy may fall asleep while writing a letter, driving a car, or carrying on a conversation. Individuals with this dysfunction have recurring, irresistible attacks of drowsiness, and simply fall asleep at inappropriate times. These can occur for a period of a few seconds anywhere to 30 minutes and in severe cases occur several times in a day.
Nightmare - Nightmares are dreams that usually occur in the last three hours of sleep during a REM period. Nightmares are terrifying dreams in which our worst fears are brought to life in convincing detail. Nightmares are almost always long and intense. Some people may wake up after a nightmare in a cold sweat and can sometimes keep people from getting a good nights sleep. But as all problem dreams they can be overcome by facing up to what they can mean in your life.
Non-Rapid Eye Movement (NREM) Sleep - Stages 1-4 of sleep are often categorized into NREM sleep. In this stage the body is in a higher state of wakefulness than that of REM sleep. Observations show that NREM sleep is characterized by an idle brain and relaxed body. It is in this stage which sleep walking and sleep talking both occur.
Out of Body Experience (OBE) - An OBE is a personal experience where a person feels they are perceiving the physical world from a location outside their physical bodies. OBEs usually have a highly positive lasting impact on the people who have experienced them.
Parapsychology - Meaning "beside psychology," parapsychology is a subfield of psychology that studies psi phenomena, things such as extrasensory perception, telepathy, and psychokinesis. It is also known as psychical research.
Perception - A general term to describe the whole process of how we come to know what is going on around us: the entire sequence of events from the presentation of a physical stimulus to the phenomenological experience of it. Perception is viewed as a set of subprocesses that occur in a multi-level, interactive system. The lower levels in this system, the parts closely associated with the sense organs, are called sensory processes.
Physiology - The study of the physical and chemical processes that take place in living organisms during the performance of life functions. It is concerned with such basic activities as reproduction, growth, metabolism, respiration, excitation, and contraction as they are carried out within the fine structure, the cells, tissues, organs, and organ systems of the body.
Polygraph - A device that measures simultaneously several physiological responses that accompany emotion; for instance, heart and respiration rate, and blood pressure. It is commonly known as a "lie detector" because of its use in determining the guilt of a subject through responses while he or she answers. It is commonly used in sleep research to monitor EEG, EOG, and EMG readings of a subject.
Reality Testing - Reality testing is a method for inducing lucid dreams. There are many techniques and different people have different ways of doing so.
Rapid Eye Movement (REM) Sleep - Also known as paradoxical or active sleep, this stage of sleep is where dreaming usually occurs. It is recognized by very alert brain waves and high muscular tension. Sometimes the brain has been known to be more active in this state than in a wakeful state. The name is given from a noticeable eye movement during this stage of sleeping.
Schema - Psychologists use this term to designate specific theories and ideas about mental events. This term refers to cognitive structures stored in memory that are abstract representations of events, objects, and relationships in the real world. It is a key ingredient of cognitive theories psychological phenomena.
Sensory Processes - The subprocesses of the perceptual system that are closely associated with the sense organs. Sensory processes provide selectively filtered information about the stimuli that impinge on us; higher-level processes use this information to form a mental representation of the scene.
Sleep Paralysis - Sometimes known as REM atonia, is a motor inhibition of the legs, arms, and body of the sleeper during REM sleep. It is our own bodies security against acting out our own dreams or else we would be active throughout the night. The sleep paralysis of REM sleep does not always automatically turn off when you come out of the REM state. This is why you may wake up and not be able to move for a few seconds. It may seem a bit terrifying, but it happens to everyone during the night, and nothing bad can come of it.
Somnambulism - This term is better known as sleep walking. Some say that this occurs from people acting out a dream, but this is not the case. Since the body is paralyzed during REM sleep it would be unable to act out a dream. People that have been woken after sleep walking very rarely remember what they have been dreaming.
Spindles - Short runs of rhythmical responses of 12-16 hertz that have been recorded on an EEG.
Theta Waves (4 - 7 cycles per second) - These are found in adults who are extremely relaxed. They are associated with creativity, high suggestibility, and flashes of inspiration.
Wake Initiated Lucid Dream (WILD) - This describes a lucid dream where the dreamer went straight into a lucid dream from the waking state with unbroken awareness. WILD's are not nearly as common as DILD's.