You spend about one-third of your life sleeping, but it’s still something many struggle with. Researchers and experts also struggle with it because of the mysteries surrounding how and why we sleep and what happens to us while we do.

Relaxing sleep music (8 hours) with soft piano music and water sounds. This soothing sleeping music is produced to hopefully make you fall asleep fast. Strea...

8 Hours of Relaxing Sleep Music Sleeping Music, Relaxing Music, Fall ...

Fifty years of research on brain activity and physiological patterns of sleeping has revealed a great deal about what sleep is and what it is not. We all have at least a vague notion of what sleep is, but that doesn't mean that defining this mysterious part of our lives is simple.

It has a powerful, muscular body with a large head and paws, a long tail and orange fur with black, mostly vertical stripes. It is traditionally classified into nine recent subspecies, though some recognise only two subspecies, mainland Asian tigers and the island tigers of the Sunda Islands.

tiger, (Panthera tigris), largest member of the cat family (Felidae), rivaled only by the lion (Panthera leo) in strength and ferocity; it is a famous apex predator (meaning without a natural predator or enemy).

The tiger is a large, carnivorous mammal and the largest living big cat. Their distinctive fur is orange and white with dark vertical stripes. The pattern of stripes is unique to each individual.