2006-09-18 03:56:04 · 13 answers · asked by rianna_ket 1 in Health ➔ Other - Health
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 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 but 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 in the regulation of circadian rhythms. The SCN is influenced by external light 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.
2006-09-18 04:00:03 · answer #1 · answered by College Kid 5 · 0⤊ 0⤋
Our bodies need rest to function properly. Metabolism and brain functions are more effective when given time to rest. Try staying awake for 24 hours or more and you will see you cannot think straight, you will feel sick, you may even get sick because your immunity depreciates. Some think we sleep to look better. Study's show that this isn't true, we just feel better, so we think we look better. Over time I do believe no recuprative sleep can cause many ailments like depression, eating disorders, bodily pain, illnesses. It's a good idea to get a good nights sleep every night. It does a body good.
2006-09-18 04:08:13 · answer #2 · answered by Anonymous · 0⤊ 0⤋
our eyes are always working . so we give rest by way of sleeping
2006-09-18 03:59:57 · answer #3 · answered by guharamdas 5 · 0⤊ 0⤋
It allows the mind to somewhat rest.
2006-09-18 04:03:40 · answer #4 · answered by *AstrosChick* 5 · 0⤊ 0⤋
To let our body recuperate. Gravity is rough on the bones...
2006-09-18 04:03:10 · answer #5 · answered by JustCurious 2 · 0⤊ 0⤋
to repair our tired body from a long day at work
2006-09-18 04:03:45 · answer #6 · answered by nas88car300 7 · 0⤊ 0⤋
in order to repair our bodies and to grow.
2006-09-18 03:57:58 · answer #7 · answered by thana 1 · 0⤊ 0⤋
To have wet dreams and fart at leisure.
2006-09-18 03:58:38 · answer #8 · answered by Anonymous · 0⤊ 0⤋
so we can dream up questions like this
2006-09-18 14:35:17 · answer #9 · answered by Anonymous · 0⤊ 0⤋
our bodies need to regenerate.
2006-09-18 03:58:10 · answer #10 · answered by cmp8423 3 · 0⤊ 0⤋