Free topic:about sleep

  Recent study shows that people who sleep shortly become older than people who sleep longly.
Also, study shows that average time of sleep is associated with cognitive function.
In fact, it is important for us to keep sleep.
Sleep has four part for human`s health.
  First, it means rest.
We can rest our brain and body to sleep.
  Second, it means growth hormone secretion.
While we sleep, we secrete growth hormone.
Growth hormone helps children grow up.
However growth hormone is essential for adults.
If we don`t secrete growth hormone, we get body wastes.
  Third, it means immunity.
While we sleep, we get natural immunity.
  Last, it means elimination of stress substances.
While  we sleep, it helps us regain function of a nerve cell and eliminate causative agent of stress.
  Therefore if we don`t have enough sleep, we`ll have a bad influence.
To conclude, we shoud sleep well.
Thank you.