PSY 4127 Lecture Notes - Lecture 2: International Sleep Products Association, Sleep Debt, Insomnia
4 Jun 2018
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January 15th, 2018
Lecture 2: Phylogeny and Ontogeny, The Evolution and Life Cycles of Sleep
Hibernation is not sleep.
• a seasonal rather than circadian rhythm
• can last for days, weeks or months
• biologically distinct rhythm unrelated to asleep
• bears do not necessarily always hibernate for the whole winter, sometimes it is days or weeks, sometimes not
at all if their environment has a lot going on
Circa meaning rythem, Dian meaning day.
Hibernation is often seen as a survival method, characterized by suppressed body temperature and energy
conservation.
• Hibernation is more about the body
• sleep is more about the brain
Heavy Sleepers
i. Opossum: 18 hours of sleep and 7 hours of REM
ii. Armandillos: 20 hours of sleep
iii. Koalas: 15 hours of sleep
iv. Little brown rat and little brown pocket mouse: over 20 hours of sleep.
Light Sleepers
i. Horses: just two hours of non-REM sleep standing up. They get 1 hour of REM every few days and need to
lie down for this.
ii. Sharks: nurse sharks have adapted their gills so they can rest on the sea bottom.
iii. Great White Sharks: at night they hug the coastline and stay in shallow water, their jaws gape open, they
seem catatonic, facing into the current they don’t move much and just drift in the current, similar to birds
who glide while they sleep during migration
Dolphins
• sleep one hemisphere at a time, can swim to the surface and breathe during sleep
• keep the contralateral eye open
Dinosaurs
• no fossilized organs of sleep (ie. the brain)
• similar gross anatomy to other reptiles
Birds are the only non-mammals who get REM sleep.
• it is hard to infer how this happened when they are more closely related to reptiles
We are most evolutionarily similar to monkeys but we have very different sleep. They get more slow wave, and
more REM and don’t really spend that much time awake. It looks like we are closest to foxes or moles.
Domesticated animals such as cats or lab rats sleep more. Rats do not sleep in mono phases but are more
polyphasic — they kind of just sleep whenever.
Even animals who are the same genetic/phylogenetic order have very different sleep times. We evolved close to
owl monkeys but they sleep for 17 hours.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lecture 2: phylogeny and ontogeny, the evolution and life cycles of sleep. Hibernation is often seen as a survival method, characterized by suppressed body temperature and energy conservation: hibernation is more about the body, sleep is more about the brain. Heavy sleepers: opossum: 18 hours of sleep and 7 hours of rem, armandillos: 20 hours of sleep, koalas: 15 hours of sleep, little brown rat and little brown pocket mouse: over 20 hours of sleep. Light sleepers: horses: just two hours of non-rem sleep standing up. Dolphins: sleep one hemisphere at a time, can swim to the surface and breathe during sleep, keep the contralateral eye open. Dinosaurs: no fossilized organs of sleep (ie. the brain, similar gross anatomy to other reptiles. Birds are the only non-mammals who get rem sleep: it is hard to infer how this happened when they are more closely related to reptiles. We are most evolutionarily similar to monkeys but we have very different sleep.
