Is it safe to drive at night in the Canadian Rockies?

Is it safe to drive at night, yes. But one has to ask, why drive it at night, it is a beautiful route that should be driven during the daylight hours to be enjoyed.

Driving through any of the western mountain ranges in North America requires a bit more attention to the road ahead of you, keeping an eye out for wildlife that may wander into the roadway. Fortunately highway departments are widening the route through the forest, cutting the trees and brush back quite a ways from the highway itself, providing a bigger gap between the forest's edge and the road. Of course the downside to this is that more grass grows in the clearing which attracts animals for grazing in the evening hours.

While the area you are driving through is inhabited by big animals: deer, wapiti, moose, bison, bear, etc, they are not a reason to avoid driving at night. Just keep your eyes open, stay alert and quit driving if you feel the least bit sleepy. Or better yet, drive through in the daytime and enjoy the view.

Qualifier: I used to live in Calgary and have driven Calgary-Vancouver many times.

As well explained in other answers, there are wildlife on the roam. But it's the mountains which adds rockfall and cliffs to the equation. The mountains can easily drop a rock the size of your kitchen table onto the highway at any time, and in some places you have the combination of single-lane traffic, tight turns and "sharp drop off pavement edge" means it's a looooong way down. They'll find your wreck in a day or two.

You can easily do Calgary to Vancouver in 12 hours. The enroute scenery is quite spectacular, and if you want to make a few stops on the way, Revelstoke or Kamloops are good mid-points.

At the west end of the drive, skip the Coquihalla Highway (#5) and use old Hwy 1 through Cache Creek and Lytton. Much nicer views and all the trucks and RVs tend to stay on the new road.

Never do this. I just got off the road in Revelstoke and am writing this after the most harrowing hour of driving along winding mountain roads in the dark with 4 semis tailgating me and oncoming semis blinding you with their headlights.
The road lines are practically non-existent and you can’t see more than 5 metres in front of you.

If you go too slow, the semis are mercilessly breathing down your neck. If you go faster, you are driving blindly into darkness.
You are always on the stressful edge between being able to see what’s in front of you or impeding traffic, never knowing if you are going to survive the next corner, and you can’t get off the road to let semis pass either as there’s no place to turn off and you can’t see them anyway if there were.

I immediately searched the internet after getting off the road to see if other people had this same experience and found this thread. My shoulder is spasming from gripping the steering wheel in a nervous death clench for 65 kms until I could finally get off the road in Revelstoke.

Do NOT drive this road in the dark unless you are a professional trucker and know what you’re doing.

Never drive in the night from Kamloops to Revelstoke, the road is one line and the truck lights go directly to your face and the road lines hard to see because of that.