Yes, it is possible in either, but the difficulty level is going to depend on how complete of an illusion you want.
The easiest effect is to simply setup a soft circle as an adjustment mask and apply an exposure increase to it. This will result in looking like there is extra light on the masked area of the shot. The problem is that it won't produce shadows or respect facial geometry, so it would look a bit more like shining a light on a painting.
You can compensate for this by roughly modeling the facial geometry and applying an actual light source in 3d in order to generate the brightening, but this would require modeling the face and matching the movements to those in the scene. Both Nuke and After Effects support calculating camera movements, but it is a complex thing to do, as is the modeling of the face and the animation of the face to fit the scene.
If you don't have weeks to dedicate to the task, it probably isn't worth bothering to try the more accurate version.
This is one of those things that is far, far more practical to handle in camera than it is in post.