An average person living an average life span will spend around 20 years asleep and experience 300,000 dreams. People can die more quickly from not sleeping than from lack of food. If a person is awake for long periods of time, they might become increasingly disorientated, maybe hallucinate, and after 10 days of no sleep eventually die. But people have survived many years without hardly any sleep. Both dreaming and non-dreaming sleep are neccessary to maintain health and vitality.
Time has no accord in dreams.
Happenings separated by decades can be brought together in the same instant. The dreamer might be transported into the past or even the future. Space has no meaning in dreams either. The only laws it obeys are its own. The dream world is very fluid.