Sleep has been regarded as a wonder because nobody has been able to justify or explain what exactly causes it. It is a state of unconscious rest that transports us to a world of dreams and helps us to escape from the real world. Good sleep is often considered necessary for the optimal growth of physical, mental and emotional development of a person. The NCERT Solutions are well researched and presented by the academic experts which makes it more informative and accurate from the exam point of view.