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Invited Commentary
September 25, 2019

What Are Factorial Experiments and Why Can They Be Helpful?

Author Affiliations
  • 1Johnson & Johnson Global Epidemiology, Titusville, New Jersey
JAMA Netw Open. 2019;2(9):e1911917. doi:10.1001/jamanetworkopen.2019.11917

Kaplan and colleagues1 report the findings of 2 studies that were part of a randomized clinical trial that aimed to determine whether a combined intervention for adolescents, using both light exposure during sleep and cognitive behavioral therapy, would encourage them to get to sleep earlier than usual, thereby increasing total sleep time. They conducted 2 similar, but somewhat different, studies.

In the first study, participants were randomly assigned to receive either 3 weeks of light flashes (light alone) or a sham light intervention. The light flashes were brief light pulses administered in 3-millisecond bursts delivered 20 seconds apart, starting 3 hours before the targeted wake time for the individual participant. In the second study, participants were randomized to a combination of light plus cognitive behavioral therapy or sham light therapy plus cognitive behavioral therapy. The main outcomes were self-reported sleep times, momentary ratings of evening sleepiness, and subjective measures of sleepiness and sleep quality.

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