[andai]

Sure, but when are they exposed to darkness? When there's a power outage, which hasn't happened within my lifetime.

I'm pretty sure if I had to live with lamps shining on my face all night it would disrupt my circadian rhythm, regardless of when I naturally prefer to sleep.

[pavelrub]

The point is that deer being active at night isn't an indication of street lamps disrupting their ciradian rhythm. It's possible that those street lamps do affect it, but the behavior you saw isn't evidence of that.