Running and sleep. Sufficient sleep is important for adolescents for both their neural and psychological development. Despite this, daytime sleepiness and poor physical and psychological functioning related to chronic sleep disturbances are common. There is a growing body of evidence that exercise is associated with both better sleep and improved psychological functioning. Sixty participants were recruited from a high school in northwestern Switzerland. They were randomly assigned to either a running group or a control group, 30 to each group. The running group ran every morning for a little over 30 minutes on weekdays for a three-week period. All participants used a sleep log for subjective evaluation of sleep, and sleep was also objectively assessed at the beginning and end of the study using a sleep electroencephalographic device that measured quantities such as sleep efficiency and time spent in the four different sleep phases. Running was found to impact positively on both objective and subjective measures of sleep functioning. What are the explanatory and response variables