Endogenous pacemakers + exogenous zeitgabers

Question 1

Endogenous pacemakers + sleep/wake cycle
(suprachiasmatic nucleus)

Answer 1

SCN
Nerves in hypothalamus
Receive info about light via optical nerves, even with closed eyes

Adjust to daylight with eyes closed

“master clock” - uses external light levels to determine circadian rhythm

SCN adjusts bio clock depending to light levels

Question 2

Animal study SCN

Answer 2

Destroyed SCN connections in 30 chipmunks

released into wild
monitered 80 days

Sleep/wake cycle disappeared

SCN couldn’t receive info about light levels outside

Question 3

Pineal gland + melatonin

Answer 3

SCN passes info about day length + light to penial gland

night - gland produces melatonin
light ^ SCN sends signals to decrease melatonin

Determined by outside world

Question 4

Exogenous zeitgebers and sleep/wake cycle

LIGHT

Answer 4

Light can reset endogenous pacemaker - SCN
Indirect influence on hormone + blood circulation

Shone light on backs of knees, changed sleep/wake up to 3 hours

Question 5

Social cues

Answer 5

Stimuli such as meal times, work and social activities
Infants = random sleep/wake
16 weeks = babies entrained, paretns teach meal time + bed times

Adapting to local time meal + sleep = beat jetlag

Question 6

AO3

Answer 6

Ethics -
Many chipmunks died

Overstated-
normal sleep pattern in arctic regions

No replication - light study

Research ONLY studies endogenous pacemakers, lacks validity
No sense to separate