Sleep in invertebrates Sleep in non-human animals

caenorhabditis elegans primitive organism in sleep-like states have been observed.



a cuckoo bee genus nomada, sleeping. note characteristic position anchored mandibles. bees have of complex sleep states amongst insects.

sleep phenomenon appears have old evolutionary roots. unicellular organisms not sleep , although many of them have pronounced circadian rhythms. nematode c. elegans primitive organism in sleep-like states have been observed. here, lethargus phase occurs in short periods preceding each moult, fact may indicate sleep primitively connected developmental processes. raizen et al. s results furthermore suggest sleep necessary changes in neural system.

the electrophysiological study of sleep in small invertebrates complicated. insects go through circadian rhythms of activity , passivity not seem have homeostatic sleep need. insects not seem exhibit rem sleep. however, fruit flies appear sleep, , systematic disturbance of state leads cognitive disabilities. there several methods of measuring cognitive functions in fruit flies. common method let flies choose whether want fly through tunnel leads light source, or through dark tunnel. normally, flies attracted light. if sugar placed in end of dark tunnel, , flies dislike placed in end of light tunnel, flies learn fly towards darkness rather light. flies deprived of sleep require longer time learn , forget more quickly. if arthropod experimentally kept awake longer used to, coming rest period prolonged. in cockroaches rest period characterized antennae being folded down , decreased sensitivity external stimuli. sleep has been described in crayfish, too, characterized passivity , increased thresholds sensory stimuli changes in eeg pattern, markedly differing patterns found in crayfish when awake.