What is Sleep: Definition and 163 Discussions

Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with sleep displaying different, active brain patterns.
Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. A well-known feature of sleep is the dream, an experience typically recounted in narrative form, which resembles waking life while in progress, but which usually can later be distinguished as fantasy. During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems. The internal circadian clock promotes sleep daily at night. The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research. Sleep is a highly conserved behavior across animal evolution.Humans may suffer from various sleep disorders, including dyssomnias such as insomnia, hypersomnia, narcolepsy, and sleep apnea; parasomnias such as sleepwalking and rapid eye movement sleep behavior disorder; bruxism; and circadian rhythm sleep disorders. The use of artificial light has substantially altered humanity's sleep patterns.

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  1. LaraKnowles

    Medical Can people can breathe through their mouth during sleep?

    There was a man named Mark Gleeson who had snoring problems caused by a nose injury. He put tampons up his nostrils to try and cure his snoring, and went to bed. He suffocated in his sleep. The coroner, Michael Burgess, said the tampons contributed to him suffocating. If you believe that...
  2. .Scott

    Getting a Crying Baby to Sleep

    A study published in "Current Biology" describes a method for getting crying infant to sleep. That method: -- 1) Carry infant while walking for 5 minutes. -- 2) Continue to hold infant for another 5 to 8 minutes. In my household, this is very similar to "Daddy's method for getting the baby to...
  3. dRic2

    Low battery life in sleep mode

    I have a 6 years old MacBook air, still running the OS of a couple of years ago. Lately, battery life is going down (around 4.5 hours of light/medium use) so I mainly use it as a desktop computer, connected to an external monitor. However, when I leave it in sleep mode (still on, but shell...
  4. Astronuc

    Biphasics sleep patterns in pre-industrial England/Europe

    BBC has an interesting article on sleep patterns in pre-industrial England and Europe, and it seems natural in other animals. https://www.bbc.com/future/article/20220107-the-lost-medieval-habit-of-biphasic-sleep Historian Roger Ekirch "explains in his book, At Day's Close: A History of...
  5. C

    Why do ants need to sleep (is it because of ATP synthesis?)

    I read that "Ants Get Their Sleep Through Power Naps. A recent study of ants' sleep cycle found that the average worker ant takes approximately 250 naps each day, with each one lasting just over a minute. That adds up to 4 hours and 48 minutes of sleep per day." But why do ants need to sleep...
  6. A

    Distinction between circadian cycles and sleep?

    Is, in biology, the notion of the circadian cycle (or rhythm) that one finds also in elementary forms of life (say a paramecium) the same notion of "sleep"? If not what is its technically difference? If it is, why are then biologist surprised to observed sleep-like states in organism with...
  7. Hamiltonian

    Medical Minimum amount of sleep per night for 4 months

    I am a 17 year old male with no major health conditions. I want to know if there will be any long term effects of less sleep(and practically no sleep schedule) ranging from anywhere between 4-5 hours a night(sprinkled with occasional all-nighters) for a period of 4-5 months. a quick google...
  8. C

    Are there brainless creatures that don't sleep?

    The cells in the heart keep beating throughout your life. It doesn't sleep. So why is it not similar in the brain? Are there any brainless creatures like the heart that don't sleep?
  9. nomadreid

    Hibernate, then sleep.... who wins?

    I could think of two ways that this might be programmed: whereby the last function enabled takes precedence (in this case, sleep) or whether sleep is a sort of subset for hibernation, making "sleep" have no effect on the hibernation.
  10. N

    Why Does Lack of Sleep Affect Wound Healing?

    Let's say you hurt your finger. If you lack sleep. Why would it affect healing of the finger? Is it not the innate immune cells in the fingers and blood work isolated there? Why would lack of sleep affect the healing of the finger? Remember when we sleep, our brain is still as active as when we...
  11. S

    When did "eight hours of sleep per day" become an accepted guideline?

    When was the notion that most people need eight hours of sleep per day popularized? Was it a rule of thumb before there was any scientific research to support it? Did the notion arise after the widespread use of electric lighting - when people acquired an alternative to going to sleep when...
  12. lincolnstoller

    What Are the Diverse Topics Covered by Lincoln Stoller?

    I have a varied background in physics and biology learning from Charlie Townes, Steve Weinberg, Eugene Wigner, Ilya Prigogine, and Jerry Lettvin among not so many others. I've worked in relativistic QM, many-body QM, QM phase transitions, brain science, cognitive psychology, Western and Eastern...
  13. V

    Questions about the book "Why we sleep?"

    I'm reading the book "Why we sleep?" by Matthew Walker. If some other experts have any experience with this book could you tell me your opinion? Is our modern society really blind to very good known facts mentioned in this book? For example, a necessity to sleep at least eight hours every day...
  14. Delta2

    Central Sleep Apnea Treatment: Latest Medicines and Availability in Greece

    Hi all, I have been diagnosed with central sleep apnea. The medicine I ve been given doesn't seem to work on me. Is anyone here expert on this subject, knows what are the latest medicines for central sleep apnea and if they have been allowed in european union and more specifically in greece...
  15. .Scott

    Learning new words detected during deep sleep

    I found this article interesting: https://www.cell.com/current-biology/fulltext/S0960-9822(18)31672-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982218316725%3Fshowall%3Dtrue They played audio of word pairs during slow wave sleep and detected the learning of this...
  16. A

    Music Which music do you dislike the most?

    If you were able to vote for a certain type of music that you dislike, which would it be? This poll is inspired by the fact that I never got back to sleep after being disturbed by yet another obnoxious person playing hip-hop in his car. I am happy to start the voting.
  17. jim mcnamara

    Medical Kids who eat more fish sleep better, smarter(?)

    https://www.nature.com/articles/s41598-017-17520-w The longitudinal study, based on previous DHA and EPA research (fatty acids associated with cell membranes, especially in the brain) found that children who consumed more fish had statistically fewer sleep disorders, and were statistically...
  18. S

    Why is there a link between sleep and the immune system?

    When you don't sleep.. your immune system gets weak.. but even if you stay still or rest without sleeping.. your body should theoretically be in a restful state.. so the immune system being products of cells, Brownian motion and thermodynamics, etc. should not be related to sleep.. Yet it is...
  19. F

    Medical Understanding ATP, Fatigue, and Sleep: The Role of Cell Energy and Rest

    When our body cells are full of ATP (fuel from our mitochrondria), they are supposed to energize our biological systems.. but why do we feel fatigue when we don't sleep when we still have sufficient or ample supplies of ATP? What really cause fatigue?
  20. bhobba

    Relation Of Sleep Apnia And Low Testosterone

    A friend has severe sleep apnea and uses a Cpap machine to manage it. He also has a testosterone level of 5. He has been as low as 3. He has some testosterone replacement left but is running out so went to his GP to get some more. He refused to give him any until they find the cause of the low...
  21. Jilang

    Is Boredom Linked to Increased Sleep and Dream Stimulation?

    As I grow older I'm wondering if my increasing love of sleep is in inverse proportion to real waking stimulation in the brain. Although I can't recall all my dreams, the ones I remember are quite awesome. (For example just last night I was exchanging diaries with Richard Branson, quite bizarre)...
  22. UsableThought

    Sleep deprivation & poor brain function

    Just curious if anyone else has sleep problems or other issues that particularly interfere with learning; and if so, what are your ways of coping with or minimizing these issues? Or if you like, on the positive side, of really helping your brain out w/ healthy habits? Some background on me: I...
  23. mktsgm

    Medical Why do students struggle to stay awake in class?

    Many a time we all have faced it while sitting in a class. During lectures we have a strong urge to sleep (rather we make a strong effort not to fall asleep. Especially if you are seated in the front rows.) It is not just boredom. I feel it is only when we want to concentrate, we tend trio fall...
  24. victorhugo

    What is your sleep routine during study periods?

    I naturally fell into a habit of studying until 12 at night and taking a 70-minute nap at around 4pm. This adds up to a bit over 8 hours of sleep. This way I can refresh my brain in the afternoon and study with more brain power during the calm night!
  25. F

    The Mystery of Sleep: Uncovering the Secrets of Why We Need It

    Why we sleep is said to be one of the greatest unsolved mysteries of science. Haven't they cracked it yet? is there any animal or even living system that doesn't sleep?
  26. P

    Can We Survive Without Sleep and What Makes it So Crucial?

    Why do we need to sleep, why we have allucination, feel bad and die if we don't? What happens in our brain and what makes sleeping so special and Important? Will we be able to develop some chemicals or something that allows us to stay awake without troubles or problems some day and avoiding the...
  27. Frozen

    B Can I Test Lightboxes for UV Rays?

    Hi everyone, I suffer from Delayed Sleep Phase Disorder: https://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder I've been taking sleeping pills for it for years (without them, I'd never be up in time for work) but have recently become concerned about adverse consequences of long-term use...
  28. victorhugo

    Student in need of advice on sleep schedule

    I just thought, who better to ask than those who have been through this phase and deal with students on a regular basis? Anyway, I'm just a lot more creative and productive at night, but need to get up at 8AM for school. How do I get enough sleep so that I'm not a sleep deprived zombie after a...
  29. victorhugo

    Schools Dealing with sleep as a night owl university student?

    The "10PM - 7AM" sort of sleep just doesn't work for me. I've been getting a lot more studying done by sleeping 2am-8am and napping for as long as I can (which is an unstable 00:10 - 01:20 hours) in the afternoon, but I'm noticing the side effects of sleep deprivation in my cognitive...
  30. OrangeDog

    Dealing with Sleep Apnea: Tips and Treatments for Managing Symptoms

    Im tired all the time, it is a pain in the ass. I've tried the CPAP therapy for a year now with mixed results. Does anyone here live with sleep apnea? Anyone have any luck with verious treatments?
  31. victorhugo

    Studying Need help finding an ok sleep schedule while in school

    I'm in my last year of school. I am more productive late at night, and i feel depressed/trapped if i try to force myself to sleep early. So i thought of 2 different ways that will allow me to work late at night and get at minimum 8h sleep a day: Get home from school at 3pm, sleep until 6, work...
  32. T

    How to sleep 8 hours straight?

    I am a healthy person except cannot sleep 8 hours straight. I tend to sleep for 3 to 4 hours wake up then have a lot of difficulty getting back to sleep. I'll lie awake for 2 hours then have something to eat then fall asleep again for a further 3 or 4 hours. How can I not wake up in the middle...
  33. J

    Medical Sleep and Erections: Effects of Ambien and REM Sleep on Nightly Erections

    I took Ambien (sleeping pills) for about 2 to 3 years because my mind always so active and it makes me sleep better. But stopped it about 2 months ago because the pills only made me sleep 3 hours then awake the whole time whereas now I learn how to sleep at least 5 hours without it. But I...
  34. Y

    Black screen in Win 10 after sleep

    I just up graded my older Lenovo Ultrabook U310 from Win8.1 to Win10. It worked a lot better, no more instability like before. My only problem for now is black screen after putting it to sleep. I set it so it goes to sleep when I close the lid. I do that every night, but in the morning, 70% of...
  35. Anton Alice

    Good Games for Sleep: Find the Perfect Solution

    Does anyone know a game, that is good for sleep? I have quite a signifcant problem with sleeping, and I would like to try out that, if there is something around. should not be too aggressive. Something that can be played on a laptop, while lying in bed. I tried Dirt Rally. Well, even if I sit...
  36. T

    Can I elevate a bed by 4 inches with PVC and sleep on it?

    Hi everyone, it's my first post! I need to elevate a bed by 4 inches for a while. I did some work on this problem already. Here's all the information I used to reach my conclusion: expected total weight with mattress and occupants = 220.92200 kilograms bed weight = 54 kg = 54,000 grams =...
  37. 1977ub

    Copenhagen Interpretation of Sleep / Unseen brain?

    What is the accepted interpretation of these two similar related issues: 1) When I am sleeping do my brain and body revert to un-collapsed wave state until and unless seen by a different observer? 2) I *never* have "seen" my brain - have the wave functions of the atoms and cells collapsed?
  38. Entanglement

    Medical Does Lack of Sleep Affect Cognitive Abilities and Exam Performance?

    I think I'll have to sleep for only 3 hours every night for the next month because of my final exams. Has anyone who spent a while sleeping so little ever felt significant effect on their cognitive abilities, memory, or anxiety? Accordingly, will this affect how well one does on the exam? I'd...
  39. Thermo

    I have always long sleeping hours? Why?

    For me, it's ideal to sleep 12 hours. Is it normal? I am like that since my teenage years. When it is less then 11-12 hours I always feel sleepy and it is hard to wake up. This affects my school and social life. Even I sleep earlier I need to get up late. Is there any ideal hours for general or...
  40. T

    Pearson Correlation in Sleep Studies

    Hi guys, so I've been researching sleep studies and I've been looking at comparison on devices used, and most of them seem to obtain a magnitude value based on the acceleration seen on the device by the user. What I'm wondering about though is that the comparison between devices seem to be...
  41. Drakkith

    Is Your Sleep Quality Affected by Screen Time Before Bed?

    So apparently I have issues with my sleep and according to a sleep study I had done I only spend about 1.5% of the night in stage 3 sleep. During the day I usually experience significant fatigue and it is extremely difficult to do things like read, work, calculate the cube root of pi... you...
  42. Greg Bernhardt

    Sleep loss may cause brain damage

    Shift workers beware: Sleep loss may cause brain damage, new research says http://www.cnn.com/2014/03/19/health/sleep-loss-brain-damage/index.html?hpt=hp_t2
  43. P

    Managing Sleep Deprivation in High School

    Hello everyone, I'm a junior in high school and, with an enormous workload, I don't have much time to sleep. I typically get 4-6 hours except on weekends and snow days, when I usually sleep 11-12 hours. I know that many of you have had similar experiences, whether in high school, college...
  44. O

    Is Abnormal Sleep Behavior Normal?

    First, I'm not asking for medical advice; don't get the wrong idea and delete the thread. I've been all around the world, slept in hostels, dorms, things like that. I've seen people do some strange stuff. People who seem to only sleep a few hours at night, but talk in their sleep, actually sit...
  45. M

    Understanding the Impact of an Irregular Sleep Pattern on Energy Levels

    Hello, I woke up really early today fully awake, around 5:15am. However, feeling that it was too early and taboo to be up at this time (especially on a saturday), I went back to sleep and woke up again at 8:20 am, but this time feeling very tired and groggy, not wanting to get out of bed. I...
  46. M

    Sleep vs. Cramming: Which is Better for Tests?

    Suppose you had a test in 6 hours and you are not prepared for it in the least, it would take you 6 hours to make it through each topic in enough detail to learn the material under normal circumstances. Or it would take you ~4.5 hours to briefly review each topic enough to be familiar with it...
  47. rogerk8

    Why Do Humans Need to Sleep for Optimal Functioning?

    Hi! I wonder why we have to sleep. Physical tiredness can be measured by the amount of milk acid in our muscles. But is there an measureable analogy in our brain when it comes to mental tiredness? It seems simple enough that if you use the brain too much it will have to rest. But...
  48. M

    Maximizing Sleep: The Science Behind Getting the Most Out of Your Zzz's

    Hello, I have been going on less sleep now than before (5-6 hours/day) because of a lot of schoolwork and other work, I was wondering what research there is as far as maximizing sleep as far as what little I get. For example, is it a good idea to attempt to "catch up" during the weekend by...
  49. N

    What's Your Sleep Schedule Like?

    Just wondering what everyone's sleep schedule is like. I know I usually go to bed around 1030, but recently it's been later than that. Then I have to wake up at 6, so recently I've only been getting like 6.5 hours of sleep. I know it's recommended to get 8, but is it really worth it? Also...
  50. RabbitWho

    Medical Why aren't hunger thirst and (the need to) sleep considered reflexes?

    A reflex is an automatic and involuntary response of a living thing to the presence of a stimulus. A reflex is usually a movement, but it can be the activation of secretion in a gland. Is it because there is no particular stimulus? Not having eaten, drank, slept for a while is not considered a...