I don't know if there's definitive research saying this, but this ability to fall asleep quickly may be due to sleep deprivation. However, polyphasic sleep is linked to lower academic performance and increased daytime sleepiness. [0] That makes me think that the "benefit" is possibly an illusion due to the antidepressant effect of sleep deprivation.

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[0]: Studies linked here: https://www.verywellhealth.com/pros-and-cons-of-a-polyphasic...