Gabe is a little embarrassed to admit that he sleeps more than 9 hours a night. Most of his friends brag that they sleep less than 6 hours every night. Gabe would be considered a "long sleeper" and his friends are "short sleepers." Nevertheless, Gabe has nothing to be ashamed of because research suggests that their are different.

Circadian rhythm

Explanation:

The condition given in question statement is called circadian rhythm.

Circadian rhythms are the changes that develop in humans across the day cycle and it basically responds to the light and darkness. One of the very examples of this is sleep, naturally humans tend to sleep at night while they get up in the morning or light. However the sleep timings or all the people are not same, it can differ in people also and this is not an abnormal feature

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.