Why is sleep needed?

Question

Do you know what causes it (fatal familial insomnia)? and also if a person have that, what makes them lose their ability to sleep? and also, I know sleep is needed to stay alive but what does sleep do? When we sleep, do we recharge our brains? What exactly do we recharge our brains with? chemicals? How come we cannot make the chemicals then we can go on not sleeping until we are 80 years old.

Answer 1

Sleep is the state of natural rest observed in all mammals, birds, and fish. It is characterized by a reduction in voluntary body movement, decreased reaction to external stimuli, an increased rate of anabolism (the synthesis of cell structures), and a decreased rate of catabolism (the breakdown of cell structures). In humans, sleep is necessary for life. The capability for arousal from sleep is a protective mechanism and also necessary for health and survival. Technically, sleep is different from unconsciousness
The cycle between sleep and wakefulness involves different stages of sleep. Currently, scientists divide sleep into two general types: REM (Rapid Eye Movement) and NREM (non-REM). REM sleep is characterized by desynchronization of the electroencephalograph (EEG), loss of skeletal muscle tone, and sympathetic nervous system; whereas non-rapid eye movement sleep is characterized by parasympathetic nervous system activity (Legramante & Galante, 2005).
Studies of human sleep have established five well-defined stages, according to EEG recordings and polysomnography:

Non-REM sleep accounts for 75–80% of total sleep time:
Stage 1, with near-disappearance of the alpha waves seen in awake states, and appearance for the first time of theta waves. The stage is sometimes referred to as somnolence, or "drowsy sleep". It appears at sleep onset (as it is mostly a transition state into Stage 2) and is associated with the sudden twitches or hypnic jerks many people experience when falling asleep. While these are normal and of no concern, the hypnagogic hallucinations which some people may experience at this stage can be more troublesome. During this period, the subject loses some muscle tone, and conscious awareness of the external environment: Stage 1 can be thought of as a gateway state between wake and sleep.
Stage 2, with "sleep spindles" (12–16 Hz) and "K-complexes." The EMG lowers, and conscious awareness of the external environment disappears. This occupies 45–55% of total sleep.
Stage 3, with delta waves, also called delta rhythms (.5–4 Hz), is considered part of slow-wave sleep (SWS) and functions primarily as a transition into stage four. Overall it occupies 3–8% of total sleep time.
Stage 4 is true delta sleep. It predominates the first third of the night and accounts for 10–15% of total sleep time. This is often described as the deepest stage of sleep; it is exceedingly difficult to wake a subject in this state. This is the stage in which night terrors, bed wetting, and sleepwalking occur.
REM sleep is popularly associated with dreaming, especially bizarre, visual, and seemingly random dreams; however, dreams can also occur during sleep onset (hypnogogia) and during all stages of Non-REM sleep. REM sleep is predominant in the final third of a sleep period; its timing is linked to circadian rhythm and body temperature. The EEG in this period is aroused and looks similar to stage 1, and sometimes includes beta waves. Also known as Stage 5 sleep.
Sleep proceeds in cycles of NREM and REM phases. In humans, the cycle of REM and NREM is approximately 90 minutes. Each stage may have a distinct physiological function. Drugs such as alcohol and sleeping pills can suppress certain stages of sleep (see Sleep deprivation). This can result in a sleep that exhibits loss of consciousness but does not fulfill its physiological functions.

Each sleep stage is not necessarily uniform. Within a given stage, a cyclical alternating pattern may be observed
The cycle of sleep and wakefulness is regulated by the brain stem, thalamus, external stimuli, and various hormones produced by the hypothalamus. Some neurohormones and neurotransmitters are highly correlated with sleep and wake states. For example, melatonin levels are highest during the night, and this hormone appears to promote sleep. Adenosine, a nucleoside involved in generating energy for biochemical processes, gradually accumulates in the human brain during wakefulness though decreases during sleep. Researchers believe that its accumulation during the day encourages sleep. The stimulant properties of caffeine are attributed to its negating the effects of adenosine. However the role of adenosine is far from proven, as mice lacking adenosine receptors display normal sleep patterns and normal responses to sleep deprivation.

The suprachiasmatic nucleus (SCN) of the hypothalamus plays an important role and also generates its own rhythm in isolation. In the presence of light it sends messages to the pineal gland that instruct it to cease secreting melatonin.

Thus, three processes, each influenced by hormonal, neurological, and environmental factors, underlie sleep regulation:

A homeostatic process determined by prior sleep and wakefulness, determining "sleep need."
A circadian process determining periods of high and low sleep propensity, and high and low rapid eye movement (REM) sleep propensity.
An ultradian process.
The interrelationships and relative importance of each process and system remain uncertain
Restorative theories of sleep describe sleep as a dynamic time of healing and growth for organisms. For example, during stages 3 and 4, or slow-wave sleep, growth hormone levels increase, and changes in immune function occur. Sleep deprivation, in some studies, leads to decrements in immune function and can alter metabolism under extreme, extended sleep deprivation paradigms. However, short periods of sleep deprivation have not been conclusively shown to significantly impact organ, muscular, cardiac, or other somatic function in ways that suggest that any of these systems are primarily influenced by sleep. Overall there is currently only scant evidence in support of the restorative hypothesis.
Non-REM sleep may be an anabolic state marked by physiological processes of growth and rejuvenation of the organism's immune, nervous, muscular, and skeletal systems (but see above). Sleep might restore neurons and increase production of brain proteins and certain hormones. Wakefulness may perhaps be viewed as a cyclical, temporary, hyperactive catabolic state during which the organism acquires nourishment and procreates. Also, during sleep, an organism is vulnerable; when awake it may perceive and avoid threats. Asking the question "Why do we awaken?" instead of "Why do we sleep?" yields a different perspective toward understanding how sleep and its stages contribute to a healthy organism.
According to the ontogenetic hypothesis of REM sleep, the activity occurring during neonatal REM sleep (or active sleep) seems to be particularly important to the developing organism (Marks et al., 1995). Studies investigating the effects of deprivation of active sleep have shown that deprivation early in life can result in behavioral problems, permanent sleep disruption, decreased brain mass (Mirmiran et al. 1983), and an abnormal amount of neuronal cell death (Morrissey, Duntley & Anch, 2004). Given sleep's heterogeneous nature, however, no single theory predominates, as it is difficult to describe one single "function" of sleep.
One process commonly believed to be highly dependent on sleep is memory. REM sleep appears to help with the consolidation of spatial and procedural memory, while slow-wave sleep helps with the consolidation of declarative memories. When experimental subjects are given academic material to learn, especially if it involves organized, systematic thought, their retention is markedly increased after a night's sleep. Mere rote memorization is retained similarly well with or without an intervening period of sleep. Some memory theorists argue that saving memory directly into long-term memory is a slow and error prone process, and propose that cerebral input is saved first in a temporary memory store, and then encoded and transferred into long-term memory during sleep. (Zhang, 2004).

Despite an abundance of positive findings in support of these ideas, many sleep scientists do not believe that sleep's primary function is related to memory. These scientists point out that many of the studies cited by proponents of this theory are contradictory or confounded by the side-effects caused by the experimental manipulations. A more salient issue is that only a handful of studies have shown that sleep actually influences brain plasticity--which is the mechanism underlying remembering and forgetting (Benington and Frank, 2003).
One view, "Preservation and Protection", is that sleep serves an adaptive function. It protects the individual during that portion of the 24-hour day in which being awake, and hence roaming around, would place the individual at greatest risk. Organisms don't require 24 hours to feed themselves and meet other necessities. From this perspective of adaptation, organisms are safer by staying out of harm's way where potentially they could be prey to other stronger organisms. They sleep at times that maximize their safety, given their physical capacities and their habitats. (Allison & Cicchetti, 1976; Webb, 1982). This theory, however, is not universally accepted. For example, if true, there would be no reason for the brain to disengage from the external environment as it does during normal sleep. A more advantageous adaptation would be for animals to seclude themselves but maintain quiet wakefulness to avoid predation. The fact is that sleep is itself a "drive" in that animals will alter their behaviors in order to obtain sleep: sleep is not simply a passive consequence of removing the animal from the environment. Therefore, circadian regulation is more than sufficient to explain periods of activity and quiescence that are adaptive to an organism but the more peculiar specializations of sleep most likely reflect different and unknown functions.
These several theories are not mutually exclusive; each may contain truths that will be validated in the future. Despite decades of intense research, scientists still have only clues to sleep function.
Recent research suggests that sleep patterns vary significantly across cultures. The most striking differences are between societies that have plentiful sources of artificial light and ones that do not. The primary difference appears to be that pre-light cultures have more broken up sleep patterns. For example, people might go to sleep far more quickly after the sun sets, but would then wake up several times throughout the night, punctuating their sleep with periods of wakefulness, perhaps lasting several hours. The boundaries between sleeping and waking are blurred in these societies. Some observers believe that sleep in these societies is most often split into two main periods, the first characterised primarily by "slow sleep" and the second by REM sleep. This is called segmented sleep, which led to expressions such as "first sleep" "watch" and "second sleep" which appear in literature from all over the world in pre-industrial societies.

Some societies display a fragmented sleep pattern in which people sleep at all times of the day and night for shorter periods. For example, many Mediterranean societies have a siesta, in which people sleep for a period in the afternoon. In many nomadic or hunter-gatherer societies people will sleep off and on throughout the day or night depending on what is happening.

Plentiful artificial light has been available in the industrialised west since at least the mid-nineteenth century, and sleep patterns have changed significantly everywhere that lighting has been introduced. In general people sleep in a more concentrated burst through the night, and sleep much later, although this is not always true.

In some societies people generally sleep with at least one other person, often many, or with animals. In others people rarely sleep with anyone but a most intimate relation such as a spouse. In almost all societies sleeping partners are strongly regulated by social standards. For example, people might only sleep with their immediate family, extended family, spouses, with their children, with children of a certain age, children of specific gender, peers of a certain gender, friends, peers of equal social rank, or with no one at all. Sleep may be an actively social time depending on the sleep groupings, with no constraints on noise or activity.

People sleep in a variety of locations. Some sleep directly on the ground, others on a skin or blanket, others sleep on platforms or beds. Some sleep with blankets, some with pillows, some with simple head rests, some with no head support. These choices are shaped by a variety of factors such as climate, protection from predators, housing type, technology, and the incidence of pests.

Cattle, horses, and sheep are unique in that they can sleep while standing, though none may experience REM sleep in this position, for REM sleep causes partial muscle paralysis. For REM sleep to take place, the animals must lie down. Conversely, birds may have periods of REM sleep while perched. Some breeds of dogs usually sleep throughout the day like cats, while other breeds have only one daily sleep session. While dreaming, dogs may make a quiet barking sound while both cats and dogs may make running motions with their legs.

you want so much.....

Answer 2

Physically we don't need it. I don't think its so much a recharge for the brain as it is a chance to clear alway the clutter. Much like defragging a hard drive. Apparently all warm blooded animals sleep at least a little.

If you force yourself to go with out sleep your brain function as far as being able to reason starts to go down. Sorry by the time your 80 you will have wasted at least 20 years sleeping.

Answer 3

Scientists and Doctors do not yet understand why we need sleep. They do know that we do need sleep. Staying constantly awake for more than about 11 days will cause death. The brain doesn't need to be 'recharged' as if it were a battery. Still there is something that happens to our nerological systems (brain, brainstem, etc) when we go to sleep that helps it function better when we awaken.

Answer 4

Insomnia (sleeplessness) is due to stress, dietary and medical
problems. By making small lifestyle changes like having a fixed
daily routine, relaxing and eating properly, insomnia can be
cured. I found the information at http://tinyurl.com/jfzpz useful
for getting sleep.

Answer 5

So we can be refreshed. There was one night that I couldn't sleep and the next day I was tired. I couldn't sleep because I was worried, so it is to make our bodies refresh and be recharged for the next day.

Answer 6

we need rest/sleep to re-energize ourselves. even your heart will rest between beats.

Answer 7

It isn't needed. It's just something we choose to do. Hmmmmm

Answer 8

Don't post the same stuff over and over again, it's annoying.

Answer 9

is neccesary to recover the enegy