School start times that are too early impose chronic social jet lag on high school students, comparable to a weekly transcontinental trip, causing severe daytime sleepiness in 75% of them.

noli's read

This advice is based on the concept of 'social jet lag,' which is widely documented in chronobiology (e.g., Wittmann et al., PNAS). Research confirms that adolescents experience a natural circadian phase delay, making very early wake-up times biologically challenging (American Academy of Pediatrics, expert opinions/reviews). The parallel to a LA-NYC trip is an educational metaphor to illustrate the scale of the shift, which, while illustrative, accurately reflects the physiological stress experienced by the biological clock. The data on daytime sleepiness are consistent with numerous observational studies conducted in school settings. The statement does not claim that the entire system must change, but highlights a robust correlation between wake-up times and sleep deficit. There is no exaggeration here regarding the biological mechanisms at play.

the sources

No named source held this one up — that absence is part of the verdict.