With the aid of IR LEDs, & IR cameras it's now quite easy to shoot in visual darkness. This was something one of my early IR cameras specialised in having a built in IR illuminator & and a switch to remove the hotmirror. For reasons known only to Sony they made it difficult to use the camera in daytime for IR!
Here's a portrait of one of my sons shot in near complete darkness:
nightshot portrait by Mike Kanssen, on Flickr
And here is a horrible selfie done with an IR filter over the pop up flash
IR flash selfie by Mike Kanssen, on Flickr
Trail cameras will often use this approach too...