Sleep & Dreams

Circadian Rhythm

A biological clock that is genetically programmes to regulate physiological responses within a time period of 24 hours (about a day); one example is the sleep-wake cycle.

Narcolepsy

A chronic disorder marked by excessive sleepiness, usually in the form of sleep attacks or short periods of sleep throughout the day. The sleep attacks are accompanied by brief periods of REM sleep and loss of muscle control, which may be triggered by big emotional changes.

Reticular Formation

A column of brain cells that arouses and alerts the forebrain and prepares it to receive information from all the senses. It plays an important role in keeping the forebrain alert and producing a state of wakefulness. Animals or humans whose reticular formation is seriously damaged lapse into permanent unconsciousness or coma.

Sleep Apnea

A condition characterized by a cycle in which a sleeper slops breathing for interval of 10 seconds or longer, wakes up briefly, resumes breathing, and returns to sleep. This cycle can leave apnea sufferers exhausted during the day but oblivious to the cause of their tiredness. It is more common among habitual snorers.

Jet Lag

A condition in which travelers' internal circadian rhythm is out of step, or synchrony, with the external clock time at their new location. They experience fatigue, disorientation, lack of concentration, and reduced cognitive skills. It takes about one day to reset the circadian clock for each hour of time change.

Sleep

A condition in which we pass through five different stages, each with its own level of consciousness, awareness, responsiveness, and physiological arousal. In the deepest stage of sleep, we enter a state that borders on unconsciousness.

REM Behavior Disorder

A disorder, usually found in older people, in which the voluntary muscles are not paralyzed during REM sleep; sleepers can and do act out their dreams.

(VLPO) Ventrolateral Preoptic Nucleus

A group of cells in the hypothalamus that act like a master switch for sleep. When turned on, the VLPO secretes a neurotransmitter (GABA) that turns off areas that keep the brain awake. When the VLPO is turned off, certain brain areas become active and you wake up.

Melatonin

A hormone secreted by the pineal gland, an oval group of cells in the center of the human brain. Melatonin secretion, controlled by the suprachiasmatic nucleus, increases with darkness and decreases with light; thus, it plays a role in the regulation of circadian rhythms and in promoting sleep.

Questionnaire

A method for obtaining information by asking individuals to read a list of written questions and to check off, or to rate their preference for, specific answers.

Seasonal Affective Disorder (SAD)

A pattern of depressive symptoms that cycle with the seasons, typically beginning I fall or winter. The depression is accompanied by feeling of lethargy, excessive sleepiness, overeating, weight gain, and craving for carbohydrates.

Suprachiasmatic Nucleus

A sophisticated biological clock, located in the hypothalamus, that regulates a number of circadian rhythms, including the sleep-wake cycle. Suprachiasmatic cells are highly responsive to changes in light.

Repair Theory of Sleep

A theory of sleep suggesting that activities during the day deplete key factors in the brain or body that are replenished or repaired by sleep.

Adaptive Theory of Sleep

A theory suggesting that sleep evolved as a survival mechanism, since it prevented early humans and animals from wasting energy and exposing themselves to the dangers of nocturnal predators.

Freud's Theory of Dreams

A theory that says we have a "censor" that protects us from realizing threatening and unconscious desires or wishes, especially those involving sex or aggression, by transforming them into harmless symbols that appear in our dreams and do not disturb our sleep or conscious thoughts.

Food-Entrainable Circadian Clock (Midnight Snack)

A timing device that regulates eating patterns in people and animals and might be responsible for late-night eating in people.

Dreaming

A unique state of consciousness in which we are asleep but we experience a variety of images, often in color. People blind from birth have only auditory or tactile dreams, while sighted people have dreams with astonishing visual, auditory, and tactile images.

Continuum of Consciousness

A wide range of human experiences, from being acutely aware and alert to being totally unaware and unresponsive.

Controlled Processes

Activities that require full awareness,alertness, and concentration to reach some goal. Because of the strongly focused attention they require, controlled processes often interfere with other ongoing activities.

Automatic Processes

Activities that require little aweareness, take minimal attention, and do not interfere with other ongoing activities.

Daydreaming

An activity that requires a low level of awareness, often occurs during automatic processes, and involves fantasizing or dreaming while awake.

Altered States of Consciousness

An awareness that differs from normal conciousness; such awareness may be produced by using any number of procedures, such as medication, psychoactive drugs, hypnosis, or sleep deprivation.

Drug Treatment for Insomnia

Benzodiazepines and Nonbenzodiazepines

Consciousness

Different levels of awareness of one's thoughts and feelings. Creating images in the mind, following thought processes, and having unique emotional experiences are all part of consciousness.

Insomnia

Difficulties in going to sleep or in staying asleep through the night. Associated daytime complaints include fatigue, impairment of concentration, memory difficulty, and lack of well-being. About 33% of adult Americans report some type of insomnia.

Nightmares

Dreams that contain frightening and anxiety-producing images. They usually involve great danger--being attacked, injured, or pursued. Upon awakening, the dreamer can usually describe the nightmare in considerable detail. Nightmares occur during REM sleep.

Nonbenzodiazepines

Drugs, such as Ambien, Lunesta, and Sonata, that are popular sleeping pills because they act rapidly, are of short duration, and have few cognitive side effects.

Latent Content

In Freud's theory of dreams, the hidden element of the dream that is determined by unconscious forces and of which the person is unaware.

Manifest Content

In Freud's theory of dreams, the portion of the dream that the person remembers, which are the harmless symbols.

Alpha Stage

In sleep, a stage marked by feeling of being relaxed and drowsy, usually with the eyes closed. Alpha waves have low amplitude and high frequency.

Delta Waves

Large, slow brain waves, meaning they have very high amplitude and very low frequency (less than 4 cycles per second).

Implicit (Nondeclarative) Memory

Mental and emotional processes that we are unaware of but that bias and influence our conscious feelings, thoughts, and behaviors.

Benzodiazepines

Minor tranquilizers (Valium, Xanax, Restoril) that reduce anxiety, worry, and stress by lowering physiological arousal, which results in a state of tranquility.

Morning Person

People who prefer to get up early, go to bed early, and engage in morning activities.

Evening Person

People who prefer to get up late, go to bed late, and engage in afternoon or evening activities.

Stage 1 Sleep

Stage 1 sleep is a transition from wakefulness to sleep and lasts 1-7 minutes. In it, you gradually lose responsiveness to stimuli and experience drifting thoughts and images. Stage 1 is marked by the presence of theta waves, which are lower in amplitude and lower in frequency than alpha waves.

Stage 2 Sleep

Stage 2 sleep marks the beginning of what we know as sleep. EEG tracings show high frequency bursts of brain activity called sleep spindles.

Stage 3 Sleep

Stage 3 sleep is when you begin showing some presence of slow brain-wave patterns, called delta waves.

Stage 4 Sleep

Stage 4 sleep is characterized by a consistent pattern of delta waves. Stage 4 is often considered the deepest part of sleep because it is the most difficult fro which to be awakened. During stage 4, heart rate, respiration, temperature, and blood flow to the brain are reduced, and there is a marked secretion of GH (growth hormone), which controls levels of metabolism, physical growth, and brain development.

Non-REM Sleep

Stages 1-4 of sleep, in which rapid eye movement does not occur; it makes up about 80% of sleep time.

Nondrug Treatment for Insomnia

1. Go to bed when you are sleepy, not by convention or habit. 2. Put the light out immediately when you get into bed. 3. Do not read or watch television in bed. 4. If you are not asleep within 20 minutes, sit and relax in another room. 5. Set the alarm to the same time each morning. 6. Do not nap during the day.

Activation-Synthesis Theory

The idea that dreaming occurs because brain areas that provide reasoned cognitive control during the waking state are shut down.The sleeping brain is stimulated by different chemical and neural influences that result in hallucinations, delusions, high emotions, and bizzarre thought patterns that we call dreams.

Threat Stimulation Theory

The idea that dreaming serves a biological function by repeatedly simulating events that are threatening in our waking lives so that our brain can practice how it perceives threats and we can rehearse our responses to these events.

REM Sleep

The stages of sleep in which our eyes move rapidly back and forth behind closed eyelids. This stage makes up 20% of our sleep time; in a normal night, we experience five or six periods of REM sleep, each one lasting 15-45 minutes. REM brain waves, which have a high frequency and a low amplitude, look very similar to the beta waves that are recorded when we are wide awake and alert; the body's voluntary muscles, however, are paralyzed. Dreams usually occur during our REM sleep.

Stages of Sleep

The stages of sleep refer to distinctive changes in the electrical activity of the brain and accompanying physiological responses of the body that occur as you pass through different phases of sleep.

REM Rebound

The tendency of individuals to spend proportionally longer in the REM stage of sleep after they have been deprived of REM on previous nights.

Extension of Waking Life Theory of Dreams

The theory that our dreams reflect the same thoughts, fears, concerns, problems, and emotions that we have when awake.

Light Therapy

The use of bright, artificial light to reset circadian rhythms and to combat the insomnia and drowsiness that plague shift workers and jet-lag suffer.

Unconsciousness

Total lack of sensory awareness and loss of responsiveness to the environment. It may result from a disease, trauma, a blow to the head, or general medical anesthesia.

Sleepwalking

Walking or carrying out behaviors while still asleep. Sleepwalkers generally are clumsy and have poor coordination but can avoid objects; they can engage in very limited conversation. Sleepwalking behaviors can include dressing, eating, preforming bathroom functions, and even driving a car. Sleepwalking usually occurs during stage 3 or stage 4 sleep.

Biological Clocks

The body's internal timing device that is gntically set to regulate various physiological responses for certian periods of time.

Sleep Deprivation (Effects on Brain)

Sleep deprivation can deplete the brain's vital energy stores and interfere with completing tasks that require focus and concentration, such as recalling and recognizing words and doing math problems. Sleep deprivation increases activity in the emotional centers of the brain, leading to irritability as well as interfering with the ability to make rational decisions.

Sleep Deprivation (Effect on Body)

Sleep deprivation may compromise our immune system, which increases an individual's vulnerability to viral infections and may lead to inflammation-related diseases. Also, sleep deprivation increases the production of stress hormones, elevated blood pressure, and increase plaque in coronary arteries, which are major risk factors for health conditions such as heart disease and stroke.

Night Terrors

Sleep disruptions in children that occur during stage 3 or stage 4 of sleep. They usually start with a piercing scream, after which the child wakes suddenly in a fearful state, with rapid breathing and increased heart rate. The next morning, the child has no memory of the frightening experience.