In reply to Glyno:
Plenty of people go walking at night. If you want to get a decent day's walking or climbing in Scotland in winter, you have to do a bit, on the way in, or on the way out, or both. I quite like it, especially if I have a moon and some snow. To add to the tips given above:
I don't like red lens torches. For starters, they wash out the contour lines on the map. I'm not convinced they make that much difference to night vision anyway.
Take a torch which is adjustable down to a very dim light. That way you can read a map without blinding yourself. A slightly brighter setting helps you find your footing, but don't go too bright, try to conserve your night vision.
A very bright setting is only rarely useful, but when it is it is very, very useful. I use and like a petzl myo 5 (long since discontinued) as it has all of the above features.
Carry spare batteries, the night is long. Better yet, carry a spare torch. Your main torch should be a headtorch, it just saves so much faff, but you can use a really cheap fake maglite as #2.
If you can navigate in thick mist, you can navigate in the dark. In fact I reckon it's easier. If you're new to it, avoid both at once.
Plan and expect to move slower than daylight, how much depends on terrain. On path, I reckon 4/5 normal speed, off path 1/2 normal speed. Avoid things like peat hags, they can cut your speed drastically if you can't see far. working your way through unknown/unpathed crags is also incredibly slow, and can be rather risky, so much so that if I found myself on such terrain by accident I might just wait for daylight.
Take extra warm clothes. It will be colder at night, obviously, but also you'll probably be moving about a little slower and thus generating less heat. Also, if you have enough warm clothes to just sit and wait for dawn then it gives you a comfortable safety net. It removes pressure to get down which might lead to doing something silly like entering dangerous terrain. Not always possible in proper winter though.
In fact, if you're worried about it, go out early morning rather than late night. That way dawn will come soon if you have trouble.
Poles can be handy. I use them during the day anyway, but at night they can be extra useful in crossing streams etc, as it's not always possible to see the water surface in torchlight. Taking the torch off your head and holding it to one side can help with this (it can also help with the reflections you get in thick mist).
Stay on the ball with the navigation. Even if you know the area fairly well. You lose some of your reference points at night, including the ability to just look around and estimate how far you've walked since you last thought about navigation. A GPS in the bottom of your bag can help with that, but is by no means necessary.
My main point is this though: Do not fear the darkness. It's no big thing. Have fun!