Sleeping. What happens in our body when we sleep? How much rest do we need every night and how is our body replacing damaged cells? 

Sleep is biological behavior of every animal, from little insects to mammals. It is a dynamic activity that processes to good health and well-being for other normal work. It is a natural mind state in which our sensory activity or any environmental interaction sized. During sleep we totally loss the wakefulness. It is one of the most significant human biological regenerative parts of refreshment, occupying about one -third of our life.  It has its own fundamental function for physical and mental health. While the exact functions of sleep are not clearly known, it necessarily need at regular interval of time for good and sound health. It plays like a medicine for us. It also boosts other medicines which we take during our illness. Our body frequently rolls down to sleep during night or some time during excessive eating. According to psychiatrist, it is not a loss of consciousness but a shift and this consciousness state is modified part of sensory stimulations. Our brain activities are more as compare to normal waking state.  Brain is forming the pathways that are necessary for learning and crating memories and new sights. If we avoid proper sleeping we can't focus on our work and not pay attention at all. A lack in sleep would lead to obesity, cardiovascular diseases, diabetics and other infections.

We generally sleep at night and wake up in morning. This biological work completely based on the sleep- wake cycle. This cycle depends upon need, age, external activates and many other characteristics. The cycle roughly consists 8- 16 hours a day and in human basically controlled by a combination of two internal influences i.e. sleep homeostasis and circadian rhythms. Here, in homeostasis, body maintains their steady state, in which internal conditions like body temperature, blood pressure and basal metabolic rate are normal. The time duration of night sleep is also under the homeostatic control. Adenosine is a neurotransmitter may involve in inducing sleep. As we awake with time the concentration level of adenosine rise continuously that would results in the need of sleep. Conversely, during the sleep adenosine level drastically decreases to reduce the need of sleep. It is interacting to know that secondary metabolite like caffeine binds to the adenosine receptors follow by blocking the process. On the other hand, a circadian rhyme is a cyclic change in body temperature, hormone levels and sleep- occurs over a 24- hour period. In humans, the biological clocks consists of many groups of neurons in the hypothalamus of the brain that known the suprachiasmatic nucleus (SCN). The physiological and behavioral activates along with many other external physical environment and daily social schedule are come under internal 24 hour rhythms. In this light plays a strongest synchronizing agent in humans. Alternate light and darkness are the two external signals that set the biological clock. There many physiological effects of sleep. Growth hormone, melatonin and cortisol secretion increases. There is drop in body temperature and decrease in energy loss. Skin and other tissues repair themselves rapidly.

Lack in sleep results in the accumulation of a sleep debt that must eventually be repaid. When we awake late night our body demands a nap or sleep longer, which indirectly cause some biological damages in body. Loss in hour or more in sleep may accumulate negative effect on daytime performance, mood and thinking. The conditions that are associated with a disruption of circadian rhythms include shift in day work, jet lag and other circadian rhythm sleep disorders. Insomnia is a type of disturbances in sleep onset or maintenance and in case of fatal familial insomnia body unable to sleep during emotional, instability and hallucination conditions.

Some fascinating things that happen while you are sleeping

1)      You are not sleeping deeply most of the time- Not all sleep was created equal: when you first drift off, you get only very light sleep, then progress deeper and deeper into dreamland.

2)      Your brain cleans house- Our brains are "on" throughout the night, especially in the dream heavy REM sleep, Barone says, when they are actually almost as active as they are when we're wide awake.

Among other things, they may be taking out the trash. That's one of the more exciting new ideas about the purpose of sleep: A 2013 study in mice found that waste removal systems in the brain are more active during sleep.

3) Your heart rate and breathing slow- During deep sleep all shorts of normal physiological       processes slow way down at bedtime, like heart rate and breathing. Even your muscles and organs chill out.

4)  Your blood pressure plummets- If you are fit, your blood pressure can drop by about 5 to 7 point with a good night's sleep. 

5) And so does your body temperature- During our sleep, the core temperature drops by about 2 degree.

Sleep Time Recommendations

• Newborns (0-3 months): Sleep range narrowed to 14-17 hours per day.
• Infants (4-11 months): Sleep range widened two hours to 12-15 hours.
• Toddlers (1-2 years): Sleep range widened by one hour to 11-14 hours.
• School age children (6-13 years): Sleep  range widened by one hour to

9-11hours.

• Teenagers (14-17): Sleep range widened by one hour to 8-10 hours. 
• Younger adults (18-25): Sleep range is 7-9 hours.
• Adult (26-64): Sleep range did not change and remains 7-9 hours.
• Older adults (65+): Sleep range is 7-8 hours.