The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

One of the most influential studies of human performance find that one less hour of sleep is not equal to an extra hour of achievement. In many cases the opposite occurs. When you lose an hour of sleep, it decreases your well-being, productivity, health, and ability to think the following day.
Insufficient sleep, （） performance.