From the AMA guidance directly. While color temperature is an imperfect metric to measure blue, it is what we have for now. The issue here is blue color content, and that higher color temperature LEDs emit unhealthy levels of blue when used in outdoor lighting at night.

“AMA encourages communities to minimize and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare. ”

And regarding intensity

“The AMA also recommends all LED lighting should be properly shielded to minimize glare and detrimental human health and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.”

Regarding research, from Dr. Mario Motta, one of the co-authors of the AMA guidance.

“In 2012, knowing the research activities of many scientists from around world on the effects of nighttime lighting on human physiology, I invited four prominent researchers to help me write a Council on Science and Public Health (CSAPH) report, “Light Pollution: Adverse Health Effects of Nighttime Lighting.” This 27-page report with 134 peer-reviewed references highlighted the adverse health effects of circadian rhythm disturbance. Suppressing melatonin production through excessive night lighting…”

Quoted from the abstract of your own source…

“Melatonin synthesis was tested with weekly intervals in 8 trials from 10pm to 2am (7 polychromatic illuminations and a dim light reference (<0.1 lx)) in 16 students (9 men, semi-recumbent position). Melatonin suppression was almost negligible for CCT <2000 K but increased with increasing CCT…”