Why we sleep

to state something, especially by giving an exact measurement, time, exact instructions, etc.

large in amount, value or importance

not large, strong or important enough for a particular purpose

a serious disease, especially affecting older people, that prevents the brain from functioning normally and causes loss of memory, loss of ability to speak clearly, etc. Alzheimer's is a form of dementia.

1. that is neither very good, large, hot, etc. nor very bad, small, cold, etc.

2. having or showing opinions, especially about politics, that are not extreme.

3. staying within limits that are considered to be reasonable by most people

1. to make it difficult for something to continue in the normal way

2. to cause significant change in an industry or market by means of innovation (= new ideas or methods) (business)

1. in a way that has a very great effect on somebody/something

2. very serious; completely

the chance of something happening; how likely something is to happen

a sudden serious illness when a blood vessel (= tube) in the brain bursts (= breaks open) or is blocked, which can cause death or the loss of the ability to move or to speak clearly

without real rest or sleep