Dream catcher icon

Corrosion engineering consultant

Corrosion Doctors site map

Alphabetical index of the Corrosion Doctors Web site

Dream Glossary

Alpha waves: Alpha waves are neural oscillations in the frequency range of 8 to 12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells. Neuroscientists have discovered that increasing alpha brain waves through electrical stimulation or mindfulness can boost creativity and minimize depression.

Beta waves: Normal electrical brain activity associated with active wakefulness. Beta wave, or beta rhythm, is a neural oscillation in the brain with a frequency range of between 12 and 30 Hz.

Circadian rhythms: A circadian rhythm is a roughly 24 hour cycle in the physiological processes of living beings. In a strict sense, circadian rhythms are endogenously generated, although they can be modulated by external cues such as sunlight and temperature.

Delta waves: Operating at a frequency range of 0-4Hz (the slowest of all the brainwaves), delta waves are what cause sleep to be restorative, which allow the person to wake up feeling refreshed and rejuvenated.

Dream Character: Any personality you encounter other than yourself...actually, who are you in your dreams?

Dream recall: The ability to remember all or part of a dream. Learning to remember your dreams may seem difficult at first, but if you persist, you will almost certainly succeed and may find yourself remembering four or more dreams per night.

Hypnagogia: Hypnagogia describes that magical state just before you fall asleep. At this point, you are not yet dreaming or completely unconscious, and yet you will often notice your thoughts start to drift as you slowly lose your grip on reality.

Hypnopompic state: The hypnopompic state is the transition state of semi-consciousness between sleeping and waking. For some people, this is a time of visual and auditory hallucination.

MILD or Mnemonically Induced Lucid Dream: MILD consists in telling yourself as you are in bed ready to sleep that you are going to become lucid when you dream, then visualizing yourself in a dream becoming lucid. You should repeat this incantation until falling asleep.

Non Rapid Eye Movement (NREM) sleep: Sleep comprising stages N1, N2 and N3 (slow wave sleep), characterized by slow waves and spindles in the EEG

Ponto-Geniculo-Occipital (PGO) waves: Phasic field potentials occurring immediately before and during REM sleep (originally discovered in cats). They propagate from the pontine brainstem (p) via the lateral geniculate nucleus of the thalamus (g) to the occipital visual cortex (o).

Rapid Eye Movement (REM) sleep: Sleep occurring mostly late at night, with low amplitude EEG as in wake, presence of theta activity (47Hz), reduced muscle tone, and involuntary saccadic rapid eye movements.

Reality Check: A test to establish whether you are in a dream or waking life, actively done during the day in hopes that the habit will continue within dreams.

Recurring dream: A dream that repeats the same or similar content on more than one occasion, usually on different nights

Sleep paralysis: Sleep paralysis is a temporary inability to move or speak that occurs when waking up or falling asleep. It is not harmful and should pass in a few seconds or minutes, but can be very frightening.

Slow waves: Oscillations of cortical origin that have frequencies below 4Hz. See Delta waves

Spindles: Waxing and waning oscillations of thalamic origin that have frequencies in the sigma band (1215Hz)

Stage N1 (NREM1): Sleep where the EEG is intermediate between wake and deep sleep, with presence of theta activity (47Hz), occasional vertex sharp EEG waves, and slow eye movements

Stage N2 (NREM2): Sleep occurring throughout the night, where the EEG may contain spindles and occasional slow waves

Stage N3 (NREM3)/Slow Wave: Sleep (SWS): Sleep occurring mostly early at night, with many large slow waves in the EEG.

Theta waves: The frequency range is normally between 5 and 8 Hz. A person who has taken time off from a task and begins to daydream is often in a theta brainwave state. Theta is one of the more elusive and extraordinary brain states you can explore. It is also known as the twilight state which you normally only experience fleetingly upon waking (hypnopompic), or drifting off (hypnagogia) to sleep.

WBTB: or wake back to bed lucid technique involves waking midway during the night and then letting yourself go back to sleep after possibly having taken some supplements. The hormones in your system combined with the REM sleep rich that is normal in the second part of the night greatly help to favor lucidity in dreams.

WILD or Wake-Induced Lucid Dream:  WILD consists in trying to maintain consciousness while your body falls asleep.

For further discussion, please visit and join our Dreaming is Personal group on Facebook

See also: Bibliography, Booze and dreams, Dream cycles, Dream glossary, Dream recall, Dreams and brain disorders, Dreams as a source of inspiration, Food and dreams, Herbs for dreaming, Hypnagogic state, Lucid dreaming, Neuroprotective agents, Precognitive dreams, Recurring dreams, Shamanic dreaming, Sleeping brain, Sleep deprivation, Weed and dreams, WILD, Yoga Nidra


Schematic Electroencephalogram (EEG) representation of typical brain waves

Brain waves