46 Many herbivores, like ruminantia (such as cattle spend much of their wake time in a state of drowsiness, further explanation needed which perhaps could partly explain their relatively low need for sleep. In herbivores, an inverse correlation is apparent between body mass and sleep length; big mammals sleep less than smaller ones. This correlation is thought to explain about 25 of the difference in sleep amount between different mammals. 46 Also, the length of a particular sleep cycle is associated with the size of the animal; on average, bigger animals will have sleep cycles of longer durations than smaller animals. Sleep amount is also coupled to factors like basal metabolism, brain mass, and relative brain mass. Citation needed The duration of sleep among species is also directly related to basal metabolic rate (BMR). Rats, which have a high bmr, sleep for up to 14 hours a day, whereas elephants and giraffes, which have lower bmrs, sleep only 34 hours per day.
SparkNotes: Walden: Former Inhabitants; and
42 Cortisol levels in diurnal animals typically rise throughout the night, peak in the awakening hours, and diminish during the day. 43 44 In diurnal animals, sleepiness increases during the night. Sleep duration edit different mammals sleep different amounts. Some, such as bats, sleep 1820 hours demerits per day, while others, including giraffes, sleep only 34 hours per day. There can be big differences even between closely related species. There can also be differences between laboratory and field studies: for example, researchers in 1983 reported that captive sloths slept nearly 16 hours a day, but in 2008, when miniature neurophysiological recorders were developed that could be affixed to wild animals, sloths in nature were. 45 As with birds, the main rule for mammals (with certain exceptions, see below) is that they have two essentially different stages of sleep: rem and nrem sleep (see above). Mammals' feeding habits are associated with their sleep length. The daily need for sleep is highest in carnivores, lower in omnivores and lowest in herbivores. Humans sleep less than many other omnivores but otherwise not unusually much or unusually little in comparison with other mammals.
Higher daily sleep"s and shorter sleep cycles in polyphasic species as compared to monophasic species, suggest that polyphasic sleep may be a less efficient means of attaining sleeps benefits. Small species with higher bmr may therefore have less efficient sleep patterns. It follows that the evolution of monophasic sleep may hitherto be an unknown advantage of evolving larger mammalian body sizes and therefore lower bmr. 36 Sleep is sometimes thought to help conserve energy, though this theory is not fully adequate as it only decreases metabolism by about 510. 37 Additionally it is observed that mammals require sleep even during the hypometabolic state of hibernation, in which circumstance it is actually a net loss of energy as the animal returns from hypothermia to euthermia in order to sleep. 39 Nocturnal animals have higher body temperatures, greater activity, rising serotonin, and diminishing cortisol during the night—the inverse of diurnal animals. Nocturnal and diurnal animals both have increased electrical activity in the suprachiasmatic nucleus, and corresponding secretion of melatonin from the pineal gland, at night. 40 Nocturnal mammals, which tend to stay awake at night, have higher melatonin at night just like diurnal mammals. 41 And, although removing the pineal gland in many animals abolishes melatonin rhythms, it does not stop circadian rhythms altogether—though it may alter them and weaken their plan responsiveness to light cues.
Theoretically, certain types of sleep could be possible while flying, but technical difficulties preclude the recording of brain activity in birds while they are flying. Sleep in mammals edit mammals have wide diversity in sleep phenomena. Generally, they go through periods of alternating non-rem and rem sleep, but these manifest differently. Horses and other herbivorous ungulates can sleep while standing, but must necessarily lie down for rem sleep (which causes muscular atony) for short periods. Giraffes, for example, only need to lie down for rem sleep for a few minutes at a time. Bats sleep while hanging upside down. Inversely to humans and rats, male armadillos get erections during non-rem sleep. 35 Early mammals engaged in polyphasic sleep, dividing resumes sleep into multiple bouts per day.
That is the ability to sleep with one cerebral hemisphere at a time, while the other hemisphere is awake ( Unihemispheric slow-wave sleep ). 31 When only one hemisphere is sleeping, only the contralateral eye will be shut; that is, when the right hemisphere is asleep the left eye will be shut, and vice versa. 32 The distribution of sleep between the two hemispheres and the amount of unihemispheric sleep are determined both by which part of the brain has been the most active during the previous period of wake 33 —that part will sleep the deepest—and it is also. Ducks near the perimeter of the flock are likely to be the ones that first will detect predator attacks. These ducks have significantly more unihemispheric sleep than those who sleep in the middle of the flock, and they react to threatening stimuli seen by the open eye. 34 Opinions partly differ about sleep in migratory birds. The controversy is mainly about whether they can sleep while flying or not.
Summary analysis from LitCharts
It is proposed that rem sleep evolved from short bouts of motor activity in reptiles while sws evolved from their basking state which shows similar slow wave eeg patterns. 24 Sleep in reptiles and amphibians edit reptiles have quiescent periods similar to mammalian sleep, and a decrease in electrical activity in the brain has been registered when the animals have been asleep. However, the eeg pattern in reptilian sleep differs from what is seen in mammals and other animals. 3 In reptiles, sleep time increases following sleep deprivation, and stronger stimuli are needed essays to awaken the animals when they have been deprived of sleep as compared to when they have slept normally. This suggests that the sleep which follows deprivation is compensatorily deeper. 25 In 2016, a study 26 report the existence of rem- and nrem-like sleep stages in the australian dragon Pogona vitticeps.
Amphibians have periods of inactivity but show high vigilance (receptivity to potentially threatening stimuli) in this state. Sleep in birds edit There are significant similarities between sleep in birds and sleep in mammals, 27 which is one of the reasons for the idea that sleep in higher animals with its division into rem and nrem sleep has evolved together with warm-bloodedness. 28 Birds compensate for sleep loss in a manner similar to mammals, by deeper or more intense sws ( slow-wave sleep ). 29 Birds have both rem and nrem sleep, and the eeg patterns of both have similarities to those of mammals. Different birds sleep different amounts, but the associations seen in mammals between sleep and variables such as body mass, brain mass, relative brain mass, basal metabolism and other factors (see below) are not found in birds. The only clear explanatory factor for the variations in sleep amounts for birds of different species is that birds who sleep in environments where they are exposed to predators have less deep sleep than birds sleeping in more protected environments. 30 A flamingo with at least one cerebral hemisphere awake birds do not necessarily exhibit sleep debt, but a peculiarity that birds share with aquatic mammals, and possibly also with certain species of lizards (opinions differ about that last point is the ability for unihemispheric.
9 Sleep has been described in crayfish, too, characterized by passivity and increased thresholds for sensory stimuli as well as changes in the eeg pattern, markedly differing from the patterns found in crayfish when they are awake. 10 In honeybees, it has been suggested they could be able to dream. 11 Sleep in fish edit Alternating phases of sleep and activity in an adult zebrafish main article: Sleep in fish Sleep in fish is not extensively studied. 12 Typically fish exhibit periods of inactivity but show no significant reactions to deprivation of this condition. Some species that always live in shoals or that swim continuously (because of a need for ram ventilation of the gills, for example) are suspected never to sleep.
13 There is also doubt about certain blind species that live in caves. 14 Other fish seem to sleep, however. For example, zebrafish, 15 tilapia, 16 tench, 17 brown bullhead, 18 and swell shark 19 become motionless and unresponsive at night (or by day, in the case of the swell shark spanish hogfish and blue-headed wrasse can even be lifted by hand all the way. 20 A 1961 observational study of approximately 200 species in European public aquaria reported many cases of apparent sleep. 21 On the other hand, sleep patterns are easily disrupted and may even disappear during periods of migration, spawning, and parental care. 22 Sleep in land vertebrates edit mammals, birds and reptiles evolved from amniotic ancestors, the first vertebrates with life cycles independent of water. The fact that birds and mammals are the only known animals to exhibit rem and nrem sleep indicates a common trait before divergence. 23 Reptiles are therefore the most logical group to investigate the origins of sleep. Daytime activity in reptiles alternates between basking and short bouts of active behavior, which has significant neurological and physiological similarities to sleep states in mammals.
Animals, summary & Study guide
Insects do not seem to exhibit rem sleep. However, fruit flies appear to sleep, and systematic disturbance of that state leads to cognitive disabilities. 8 There are several methods of measuring cognitive functions in fruit flies. A common method is to let the flies choose whether they want to fly through a tunnel that leads to a light source, or through a dark tunnel. Normally, flies are attracted to light. But if sugar is placed in the end of the dark tunnel, and something the flies dislike is placed in the end of the light tunnel, the flies will eventually learn to fly towards darkness rather than light. Flies deprived of sleep require a longer lined time to learn this and also forget it more quickly. If an arthropod is experimentally kept awake longer than it is used to, then its coming rest period will be prolonged. In cockroaches that rest period is characterized by the antennae being folded down and by a decreased sensitivity to external stimuli.
Unicellular organisms do not necessarily "sleep although many of them have pronounced circadian rhythms. The jellyfish Cassiopea is the most primitive organism in which wage sleep-like states have been observed. 6 The nematode. Elegans is another primitive organism that appears to require sleep. Here, a lethargus phase occurs in short periods preceding each moult, a fact which may indicate that sleep primitively is connected to developmental processes. Raizen.' s results 7 furthermore suggest that sleep is necessary for changes in the neural system. The electrophysiological study of sleep in small invertebrates is complicated. Insects go through circadian rhythms of activity and passivity but some do not seem to have a homeostatic sleep need.
criteria. 4, while some varieties of shark, such as great whites and hammerheads, must remain in motion at all times to move oxygenated water over their gills, it is possible they still sleep one cerebral hemisphere at a time as marine mammals. However it remains to be shown definitively whether any fish is capable of unihemispheric sleep citation needed. Sleep in invertebrates edit caenorhabditis elegans is the most primitive organism in which sleep-like states have been observed. A cuckoo bee from the genus Nomada, sleeping. Note the characteristic position anchored by the mandibles. Bees have some of the most complex sleep states amongst insects. 5 Sleep as a phenomenon appears to have very old evolutionary roots.
1, in the behavioral sense, sleep is characterized by minimal movement, non-responsiveness to external stimuli (i.e. Increased sensory threshold the adoption of a typical posture, and the occupation of a sheltered site, all of which is usually repeated on a 24-hour basis. 2, the physiological definition applies well to birds and mammals, but in other animals (whose brain is not as complex the behavioral definition is more often used. In very simple animals, behavioral definitions of sleep are thesis the only ones possible, and even then the behavioral repertoire of the animal may not be extensive enough to allow distinction between sleep and wakefulness. 3, sleep is quickly reversible, as opposed to hibernation or coma, and sleep deprivation is followed by longer or deeper rebound sleep. If sleep were not essential, one would expect to find: Animal species that do not sleep at all. Animals that do not need recovery sleep after staying awake longer than usual.
Walden The pond
A sleeping cat, sleep in non-human animals refers to a behavioral and physiological state characterized by altered consciousness, reduced responsiveness to external stimuli, and homeostatic regulation. Sleep is observed in mammals, birds, reptiles, amphibians, and some fish, and, in some form, in insects and even in simpler animals such as nematodes. The internal circadian clock promotes sleep daily at night in diurnal organisms (such as humans) and in the day in nocturnal organisms (such as rodents). However, sleep patterns vary widely among species. Sleep appears to be a requirement for all mammals and most other animals. Contents, definition edit, sleep can follow a physiological or behavioral definition. In the physiological sense, sleep is a state characterized by reversible unconsciousness, special salon brainwave patterns, sporadic eye movement, loss of muscle tone (possibly with some exceptions; see below regarding the sleep of birds and of aquatic mammals and a compensatory increase following deprivation clarification needed.