circadian rhythm

what occurs during the active phase?

higher energy expenditure

food and water consumed

what occurs during sleep?

energy expenditure and digestive processes decrease

cellular repair

toxin clearance

memory consolidation

information processing

what is the process of daily resetting called?

photoentrainment

to be circadian, a biological rhythm must?

1. have an endogenous free-running period that lasts approximately 24 hours. the rhythm persists in constant conditions.

2. be entrainable - able to be reset by exposure to external stimuli such as light.

3. exhibit temperature compensation - maintain periodicity over a range of physiological temperatures.

what is a zeitgeber?

a stimulus that resets the biological clock

what are examples of a zeitgeber?

temperature

social cues

physical activity

eating patterns

what does the SCN do?

allows entrainment and synchronisation

maintains control across the body by synchronising peripheral oscillators

what is the main regulator of the circadian rhythm?

melatonin

what is daylight rich in?

blue light

what does blue light trigger?

OPSIN4

what does OPSIN4 do?

inhibit melatonin, therefore promoting awareness

what is cortisol?

a steroid hormone

when is cortisol released?

in response to stress and low blood glucose concentration

what are the core circadian genes that regulate during the day?

BMAL1

CLOCK

what are the core circadian genes that regulate during the night?

period

cryptochrome

what factors cause circadian disregulation?

shift work / irregular sleep pattern / jet lag

caffeine / alcohol

light exposure

neurological conditions

what can disruption to circadian rhythm cause?

increased risk of:
obesity

cardiovascular disease

gastrointestinal problems

neurodegenerative disorders