Please review my IELTS Writing task 2. Thank you very much

Question: People sleep less than before in many countries. Why do people sleep less? What effect does it have on individually and on society?

People in many nations around the world have been suffering from sleep deprivation. This essay discusses the reason why sleep quantity has been reducing and how it affects individuals and societies.

There has been a dramatic decline in the quantity of sleep for two main reasons. First, the main reason is that stress from work or family prevents people from having a sufficient amount of sleep. In fact, people who find their mind wandering or worrying about deadlines at their workplace or family conflicts usually struggle to fall into sleep within the first one hour, reducing significantly the total of sleeping time. Another factor is that people nowadays tend to consume more and more caffeine or alcohol, which make them susceptible to sleep deprivation. By taking in too much of these substances, sleep is more likely to elude them even though they are exhausted after a long day at work.

The decline in sleep quantity is detrimental to both individuals and their society. First, sleep-deprived people’s physical health may deteriorate severely in the long run, regardless of their age. In fact, if they fail to achieve seven or eight hours of sleep in more than two months, their immune system will be weakened severely. Insufficient sleep also contributes to poor productivity, affecting negatively to the development of each society. Since tiredness caused by the lack of sleep can disturb people’s ability to focus, it seriously hampers people’s performance at work.

In conclusion, stress and substances like alcohol and caffeine are major causes of sleep deprivation that brings about devastating effects on both people’s health and the growth of society.