STUDIES:
270/
“When officers received less sleep preceding each test session, they were significantly more likely to associate Black Americans with weapons compared with when they had received more sleep. In other words, sleep restriction appeared to increase anti-Black bias."

The Stability of Implicit Racial Bias in Police Officers
Police Quarterly
Vol. 21 Issue 1, pp. 30–52,
2018
Comment on this study on its Twitter thread.