BobbyG

There are varying levels of safety.

At the low end are black-clad, unlit, non-reflective 'bike ninjas' darting in unexpected ways through the shadows.

At the high end are highly visible riders who employ be-seen clothing, strategically placed reflectors, reflective tape and lights as well as headlights lights to see the road and obstacles by.
(I also use an air horn to be heard.)

Where your comfort zone on the spectrum lies depends on how and where you ride and much risk you feel comfortable with.

I'll just mention that many cities and municipalities require bike lighting at night, and the more you ride without it, the greter your chances of being pulled over, cited and fined.