Exploring Phylogeny to Find the Function of Sleep

Phylogenetic framework

The concept that sleep states emerged early in animal evolution.

Ancestral sleep state

The belief that certain functional aspects of sleep are conserved from an ancestral sleep state.

metabolic

Sleep may have evolved fundamentally as a ________ state of the animal and serves functions outside the nervous system.

Sleep

_______ can be found in an animal with a mere 302 neurons and lacking overt circadian behavioral rhythms.

brain, CNS

Jellyfish show sleep behavior, demonstrating that neither a ______ nor a ______ is required for sleep.

Homeostatic guarding of the resting state

The observation that when a cockroach is forced to continue locomotion during its resting time, it shows an increase in subsequent immobility, suggesting:

flies

Fruit _______ display prolonged immobility during the night, are less responsive to stimulation during their quiescent period, and display immobility during the early day following forced movement during the sleep period

day, night

Jellyfish exhibit higher pulsation frequency during the ______, reduced responsiveness at ______, and reduced activity and responsiveness following forced movement at night.

early

The occurrence of REM and NREM sleep in mammals, birds, and possibly reptiles, suggesting that it was present at least as ______ as when amniotes evolved over 300 million years ago.

down, up

The understanding that brain neurons are top-________ regulators of sleep-wake states in mammals, while there is evidence of a bottom-______ organization as well.

continuum

Sleep and wake lie on a ________.

neurons

Sleep exists even in animals that lack _________