Biorhythms: Glossary

A

Ablation: the removal of body parts using laser

B

Biological clock: an innate mechanism that regulates bodily activities on a regular cycle

C

Circadian rhythms: has a 24-hour cycle

Circannual rhythms: has a more or less 1 year cycle

Core sleep: the fourth and fifth stage of sleep

D

Diurnal: active during the day

E

ECG: Electrocardiogram. Heartbeat.

EEG: Electro-encephalogram. Brainwave.

EMG: Electromyograms. Muscle tone.

EOG: Electro-oculograms. Eye movements.

Endocrine glands: glands that secrete hormones

Endogenous: internal

Endometrium: the lining of the uterus

Entrainment: the process of adjusting the biological clock my means of controlled zeitgebers

Exogenous: external

H

Hypnagogia/hypnogogic state: the transition from wakefulness to sleep, in which hallucinations may occur. This is the first stage of sleep.

Hypothalamus: a part of the brain that controls, among others, the circadian rhythms

I

Infradian rhythms: has a cycle greater than 24 hours

J

Jet lag: disruption of the biological clock caused by crossing several time zones

M

Melatonin: a hormone produced in the pineal gland that decreases brain activity, causing drowsiness

Menarche: the first menstrual period

N

Neural pathway: a set of neurons that sends nerve impulses through the nervous system

Neurotransmitter: a neurochemical that transmits nerve impulses through a synapse between neurons

Nocturnal: active during the night

NREM: Non-Rapid Eye Movement. The first, second, third, and fourth stage of sleep.

O

Oestrogen: a group of sex hormones, more abundantly found in females, that are responsible for sexual maturation

Optic chiasm: the crossing of the optic nerves from both eyes at the base of the brain

Oscillation:

P

Paradoxical sleep: another name for REM sleep, because the brain is very active while the body is paralysed

Phase advance: happens when someone travels eastbound across timezones. The day is shortened according to our biological clock.

Phase delay: happens when someone travels westbound across timezones. The day is prolonged according to our biological clock.

Pheromones: a chemical substance that is released into the air by an organism, that may affect the behaviour and/or physiology of other organisms

Phototherapy: therapy using bright light that is similar in wavelength to sunlight

Pineal gland: an endocrine gland in the brain that secretes melatonin

Progesterone: a type f hormone that prepares the endometrium of the uterus for pregnancy

Protein synthesis: the creation of protein in cells

R

REM: Rapid Eye Movement. The fifth stage of sleep.

S

SAD (Seasonal Affective Disorder): a form of clinical disorder that arises with the onset of autumn (low light levels) and disappears when the light levels rises again in late spring.

Self-report: a written or oral account of one's own thoughts, emotions, or experience

Serotonin: a monoamine neurotransmitter

Shiftwork: a workplace practice where employees work in groups according to their appointed working hours

Suprachiasmatic nucleus (SCN): the pacemaker of the biological clock, situated in the hypothalamus and connected to the optic chiasm

SWS: slow-wave sleep, the fourth stage of sleep

Synchronisation: an adjustment that makes something happen in the same time

U

Ultradian rhythms: has a cycle less than 24 hours

Z

Zeitgeber: any exogenous factors that effects the endogenous biological clock