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Do animals' also become unconscious during their sleep like humans?

  1. Jul 13, 2010 #1

    I'm not a biology or science student. So, please keep your replies in plain and straight language so you could be understood. Thanks.

    Do animals and birds also become unconscious during their deep sleep like humans? Among humans the extent to which one is absorbed in one's sleep varies, some become awake at the slightest noise, and some simply sleep like a log, or more accurately like a dead. It is my naive and general observation that animals and birds don't enter the deep sleep stage. In other words, they simply close their eyes when need to sleep, yet won't really become unaware and unconscious of their surroundings like humans.
    Last edited: Jul 14, 2010
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  3. Jul 13, 2010 #2


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    Sleep in higher animals is just the same. It mixes periods of deep slow wave sleep with REM 'dreaming' sleep.

    There are evolutionary quirks. Dolphins sleep with half their brain at a time so they can surface to breath. But brain EEG recordings make it quite easy to compare across species.
  4. Jul 13, 2010 #3


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    What do other marine mammals do o avoid asphyxiation while sleeping?
  5. Jul 14, 2010 #4


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    They do what dolphins do (it is a standard cetacean ploy).
  6. Jul 15, 2010 #5
    Hi Iron

    What do you really mean by higher animals? Animals such as humans, horses, elephants, buffaloes, etc? The animals higher on evolutionary tree. If that's the case, I would like to differ on this. I have never seen a horse so dead, dumb in sleep as human.

    I believe 'dreaming sleep' is a more intense stage than simple deep sleep. Right?

    Best wishes
  7. Jul 15, 2010 #6


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    Horses also have deep slow wave sleep sleep, but can lock their knees to sleep standing.

    Dreaming sleep (REM) is actually shallow in the sense of being near waking, while deep in that there is a tonic inhibition - basically the brain is cut off from musles - so you don't run around acting out your dreams.

    I've seen it said, horses need to lie down in REM, but not sure of the truth there.

    Horses of course sleep less because of predator issue. All species tune the amount of sleep to the nature of their lives. So cats and bats sleep a lot, horse and deer only a few hours.

    Even fish and insects have quiescent periods.

    If this is really a topic that interests you, Jim Horne of Loughborough wrote the best evolutionary stuff on sleep.
  8. Jul 15, 2010 #7


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    Ferrets are the kings of deep sleep. They can go out like a light and go almost comatose. When we got our first ferret, my wife was really upset because she thought he died, he was sleeping so soundly. You could pick him up by his hind end and dangle him upside down and he wouldn't wake up.
  9. Jul 17, 2010 #8
    Hi Turbo

    I'm happy your wife didn't go to return it! Her husband's knowledge of the animal kingdom became practical, or is it Google which deserves the credit?

    Last edited by a moderator: Sep 25, 2014
  10. Jul 17, 2010 #9
    Re: Do animals also become unconscious during their sleep like humans?

    Hi Iron

    Thank you very much for the detailed reply. I would summarize some of the points on sleep topic for my own reference and for others like me:

    Sleep is a naturally recurring state of relatively suspended sensory and motor activity, characterized by total or partial unconsciousness and the inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and it is more easily reversible than hibernation or coma. Sleep is a heightened anabolic state, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. It is observed in all mammals, all birds, and many reptiles, amphibians, and fish.

    In mammals and birds, sleeping is divided into two broad types: rapid eye movement (REM) and non-rapid eye movement (NREM or non-REM) sleep. Each type has a distinct set of associated physiological, neurological, and psychological features. NREM is further divided into three stages: N1, N2, and N3, the last of which is also called delta sleep or slow-wave sleep (SWS).

    Sleep proceeds in cycles of REM and NREM, the order normally being N1 → N2 → N3 → N2 → REM. There is a greater amount of deep sleep (stage N3) early in the night, while the proportion of REM sleep increases later in the night and just before natural awakening.

    Sleep stages and other characteristics of sleep are commonly assessed by polysomnography in a specialized sleep laboratory. Measurements taken include EEG of brain waves, electrooculography (EOG) of eye movements, and electromyography (EMG) of skeletal muscle activity. In humans, each sleep cycle lasts from 90 to 110 minutes on average, and each stage may have a distinct physiological function.

    There is relatively little dreaming in NREM. Rapid eye movement sleep, or REM sleep, accounts for 20%–25% of total sleep time in most human adults and most of the dreaming happens in this stage.

    Sleep timing is controlled by the circadian clock, sleep-wake homeostasis, and in humans, within certain bounds, willed behavior. The circadian clock—an inner timekeeping, temperature-fluctuating, enzyme-controlling device—works in tandem with adenosine, a neurotransmitter that inhibits many of the bodily processes associated with wakefulness. Adenosine is created over the course of the day; high levels of adenosine lead to sleepiness. In diurnal animals, sleepiness occurs as the circadian element causes the release of the hormone melatonin and a gradual decrease in core body temperature. The timing is affected by one's chronotype. It is the circadian rhythm that determines the ideal timing of a correctly structured and restorative sleep episode.

    Homeostatic sleep propensity (the need for sleep as a function of the amount of time elapsed since the last adequate sleep episode) must be balanced against the circadian element for satisfactory sleep. Along with corresponding messages from the circadian clock, this tells the body it needs to sleep. Sleep offset (awakening) is primarily determined by circadian rhythm. A person who regularly awakens at an early hour will generally not be able to sleep much later than his or her normal waking time, even if moderately sleep-deprived.

    Optimal amount in humans:

    Newborn - up to 18 hours
    Adolescents - 9–10 hours
    Adults, including elderly - 7–8(+) hours

    Human biological sleep:

    [SOURCE: Wikipedia]

    Iron, what I conclude is that most animals and birds can divide their sleeping time into many mini episodes as compared to humans. They don't need to take all their sleep at one time. And during those mini episodes they, probably, shuffle between different stages of sleep. Does the drawn conclusion carry any legitimacy? Please let me know.

    Best wishes
  11. Jul 17, 2010 #10


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    Re: Do animals also become unconscious during their sleep like humans?

    I don't think human sleep is different from animal sleep in any significant way. Humans can catnap. Animals can sleep longer hours. Lifestyle dictates the kinds of sleep patterns seen.
  12. Jul 17, 2010 #11
    Re: Do animals also become unconscious during their sleep like humans?

    I can't catnap. Does it mean I'm not human?! I'm sure there would be individuals who can do it but I would venture to say the number is far less. A bird which needs to sleep for one hour can distribute its sleeping over the circadian cycle in several short sleeps. Obviously, you are more knowledgeable, therefore you can better explain it.
  13. Jul 17, 2010 #12
    Re: Do animals also become unconscious during their sleep like humans?

    You know that scene in Terminator 2 when Ahnold peels off his forearm "skin" to reveal the metallic endoskeleton? Yep, that's you! :wink:

    How animals distribute their sleep doesn't change the fundamental nature of being unconscious; humans vary as well. People can experience a wide range of sleeping habits, but the fundamental nature of being at a particular level of sleep doesn't vary barring injury or illness.
  14. Jul 19, 2010 #13
    Hi Nismar

    No, I would like to be T-1000 Terminator, Arnold was T-800! T-1000 was always beating the living daylights out of T-800. You wouldn't believe it when I was a kid I watched Terminator 2 more than 50 times and the other closest match is Jurassic Park. At that time my English was very much poor and couldn't understand anything English. These two movies were simple in that I could understand the storyline by the general sequence, flow of individual scenes.

    I remember once I read somewhere that if you keep skipping few hours of your required sleep time, then you are simply accumulating those skipped sleep hours into a debt which you would have to repay sooner or later otherwise it would take a toll on your physical and psychological well being. I have heard some people saying that they catch the missed sleep of working days on weekends. I used to say to myself what a crap! Now it appears they were right. What do you say on this? But wouldn't it disrupt the circadian cycle? If one sleeps at midnight and wakes at dawn during weekdays and on weekends doubles the sleep time by waking up around noon, then wouldn't it change the fixed pattern of internal clock?
  15. Jul 19, 2010 #14
    First, I would say that the choice of the T-1000 is a good one. Second, I don't know; in my view it's not settled in the sleep-science community. You've raised some good questions that represent some of the ongoing research that is being done on behalf of the US military, and many companies.

    It is certain that we need REM sleep, and another element of normal sleep is that the longer you sleep, the shorter each interval of stage 1-REM becomes. In other words, if you sleep for 8 hours, you get more than a linear increase in overall REM sleep, which is critical to neurological function, but also muscular repair. How much REM does a person need?... that number seems to change as often as the health of the consumption of chicken eggs are called into question. I guess the short answer is: this remains to be seen. While there is a healthy average for the general population, that doesn't mean that different sleep patterns cannot work equally well.
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