A large observational study asks participants about caffeine consumption and sleep duration. The study finds that people with the largest caffeine intake have the shortest sleep duration.

Identify the relation between caffeine consumption and sleep duration.

Select the correct answer below:

Caffeine consumption and sleep duration are correlated.

An increase in caffeine consumption causes a decrease in sleep duration.

A decrease in sleep duration causes an increase in caffeine consumption.

There is no relation between caffeine consumption and sleep duration