A Glossary of Dream and Sleep-Related Terms 

Apnea - a disorder that affects breathing during sleep. Apnea can be life-threatening by cutting off your breath and putting strain on the heart.

Bes - the ancient Egyptian god of dreams

Bruxism - the grinding of the teeth during sleep.

Circadian Rhythm - the synchronized action of the body's impulse to stay awake and fall asleep.

Conscious - the waking mind policed by ethics, morality, rights and wrong. It self-imposes rules, restrictions, and regulates action and behavior

Defense Mechanism - a psychological term used to describe ways in which we protect ourselves from fear and anxiety.

Deja Vu - the peculiar feeling that a place, situation, person, action, or conversation is familiar and has already been experienced.

Ego - from the Freudian school of thought, the conscious part of one's personality that experiences the external world.

Enuresis - bedwetting. It is unrelated to dreaming as it occurs during non-REM stage of sleep where dream activity is low or non-existent..

False Awakening -  a sensation of waking and going about your morning routine when in fact you are still dreaming.  Occurs more frequently in lucid dreamers.

Hypnogogic State - the neurological mechanism in our brain that temporarily disables voluntary muscle movement when we are dreaming. It is also commonly referred to as "REM Paralysis".

Id - from the Freudian school of thought, the unconscious part of personality centered around pleasure and desire .

Insomnia - difficulty in falling asleep. waking up repeatedly or very early.

Latent Content - the underlying meaning behind the symbols in a dream.

Lucid Dreaming - the ability to consciously alter the content and control the actions in your dreams.

Manifest Content - the literal story and symbols of a dream

Morpheus - known in Greek mythology as the god of dreams.

Myoclonic Jerk - sudden muscle spasms in extremities.

Narcolepsy - a sleep disorder characterized by being able to fall asleep without warning and immediately going into REM.

Night Terrors - severe sleep disturbances occurring in non-REM sleep that produce feelings of deep fear, panic and anxiety. Night terrors are not categorized as dreams. 

Nocturnal Emissions - also known as wet dreams and occurs in males at around puberty. It is often, but not necessarily accompanied by a sexually explicit dream.

NREM - stands for non Rapid Eye Movement,

Oneirocritica - derived from Greek terminology to mean "dream interpretation".

Prodromal Dream - a dream that signals that an impending disease may afflict your body.

REM - standing for Rapid Eye Movement, it describes the stage of sleep where our eyes move rapidly back and forth. This is where the majority of dreaming occurs.

Somnambulism - sleep walking. This phenomenon most likely occurs in those between the ages of 10 to 14  who are under tremendous stress. 

Somniloquy - more commonly known as sleep talking - talking out loud while asleep. People who are under stress tend to be more likely to talk in their sleep.

Superego - from the Freudian school of thought, the censor which enforces moral codes for the ego and suppresses or blocks unacceptable impulses from the id. 

Unconscious - thoughts, memories, impulses, desires, and feelings which we are not aware of but influence our emotions and behavior in some subtle way.