I felt the study was flawed the instant I saw they tied the golden hour to a time. So if I drive a mile to cross the river into the next time zone, I can stay u

I felt the study was flawed the instant I saw they tied the golden hour to a time. So if I drive a mile to cross the river into the next time zone, I can stay up an extra hour? This study should have been tied to a concept of sleep rhythm or how long you stay up after you wake each morning. But tying it to such a poor concept of our time(which is tied to time zones which abruptly start/end at specific locations) doesn't give me much faith in the study.