Sleep: Understanding the Basics Glossary of Terms

1. Causes of Fatigue Slideshow Pictures
2. Take the Sleep Quiz!
3. Foods That Help or Harm Your Sleep Slideshow Pictures

Analysis: In psychology, a term for conversation-based therapeutic processes used to gain ...

Apnea: The absence of breathing (respiration).

Bedwetting: Involuntary urination in bed. Bedwetting is called "enuresis," from the Gree...

Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is...

Brain: The portion of the central nervous system that is located within the skull. It func...

Brainstem: The lowest part of the brain which merges with the spinal cord and provides the...

Breathing: The process of respiration, during which air is inhaled into the lungs through ...

Caffeine: A stimulant compound found naturally in coffee, tea, cocoa (chocolate), and kola...

Cardiopulmonary: Having to do with both the heart and lungs.

Cell: The basic structural and functional unit of any living thing. Each cell is a small c...

Chronic: In medicine, lasting a long time. A chronic condition is one that lasts 3 months ...

Circadian: Refers to events occurring within the span of a full 24-hour day, as in a circa...

Cognitive: Having to do with thought, judgment, or knowledge.

Coma: A state of deep, unarousable unconsciousness. A coma may occur as a result of head t...

Depression: An illness that involves the body, mood, and thoughts and that affects the way...

Essential: In medicine, of unknown cause, as in essential hypertension (high blood pressur...

Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency ...

Gastrointestinal: Adjective referring collectively to the stomach and small and large inte...

Gland: A group of cells that secrete a substance for use in the body. For example, the thy...

Growth hormone: A hormone made in the pituitary gland that stimulates the release of anoth...

Heart: The muscle that pumps blood received from veins into arteries throughout the body. ...

Heart rate: The number of heartbeats per unit of time, usually per minute. The heart rate ...

Hormone: A chemical substance produced in the body that controls and regulates the activit...

Hygiene: The science of preventive medicine and the preservation of health. Also commonly ...

Hypothalamus: The area of the brain that secretes substances that influence pituitary and ...

Immune: Protected against infection, usually by the presence of antibodies.

Immune system: A complex system that is responsible for distinguishing a person from every...

Insomnia: The perception or complaint of inadequate or poor-quality sleep due to a number ...

Jet lag: A temporary disorder that causes fatigue, insomnia, and other symptoms as a resu...

Melatonin: A hormone that is produced by the pineal gland and is intimately involved in re...

Memory: 1. The ability to recover information about past events or knowledge. ...

Metabolic: Relating to metabolism, the whole range of biochemical processes that occur wit...

Metabolism: The whole range of biochemical processes that occur within a living organism. ...

Motor: Something that produces or refers to motion. For example, a motor neuron is a nerve...

Muscle: Muscle is the tissue of the body which primarily functions as a source of power. T...

Nerve: A bundle of fibers that uses electrical and chemical signals to transmit sensory an...

Nicotine: An alkaloid (a nitrogen-containing chemical) made by the tobacco plant or produc...

NREM sleep: NREM (non-rapid eye movement) sleep is dreamless sleep. During NREM, the brai...

Parietal: Adjective from the Latin "parietalis" meaning "belonging to the wall" that the a...

Pineal gland: A small gland that is located near the center of the brain. This gland secre...

Prolactin: A hormone secreted by the pituitary gland that stimulates lactation (milk produ...

Proteins: Large molecules composed of one or more chains of amino acids in a specific orde...

REM sleep: REM sleep is the portion of sleep when there are rapid eye movements (REMs).

Skull: The skull is a collection of bones which encase the brain and give form to the hea...

Sleep: The body's rest cycle.

Sleep apnea: The temporary stoppage of breathing during sleep, often resulting in daytime ...

Sleep hygiene: A series of practices and non-medical treatments for insomnia. Sleep hygien...

Sleepwalking: Purposeful moving, usually but not always including walking, while in a deep...

Stage: As regards cancer, the extent of a cancer, especially whether the disease has spre...

Testosterone: A "male hormone" -- a sex hormone produced by the testes that encourages th...

Unconscious: 1. Interruption of awareness of oneself and one's surroundings, lack ...

White blood cell: One of the cells the body makes to help fight infections. There are seve...

White blood cell count (leukocyte count): The number of white blood cells (WBCs) in the b...

Yawning: Involuntary opening of the mouth with respiration, breathing first inward, then o...