Is it all fingers or certain ones? Carpel is certain finger and impingeement of nerves at the elbow is a different finger. However the GP test for carpel tunnel syndrome is to hold your arms out front with the elbows up and your hands together with the fingers pointing down and the backs of your hands together. hold your arms like that for some time and carpel tunnel syndrome is likely if that causes the tingling in your fingers or pins and needles.
My first suggestion is to change your pillow. If you side sleep geet a higher one that is firmer. If back sleeper get a softer and lower one. If you chop and change sleeping position then get the side sleeper / higher pillow. I found that raising my head this way made the biggest difference to my tingling. It still comes back but I readjust my body position then open and close my hands until it goes and I am usually ok then.
Other things you can do is exercises that a physio might recommend. One is the tip hand. This is where you putyour hand to the side with the fingers pointin behind you and youyr palm up. lift the fingers up to put strain on the forearm muscles. Another is to pray with your elbows up and out the side. A third I have forgotten. A physio might not diagnose it, mine had no idea at least, but they suggest exercises that can only help. For me pillow change helped most. However I am due another new pillow as they all collapse and need regular replacement. I did the exercises for a bit (like one day) so no idea if they might have helped. I think they would but I am not very good at keeping on top of such things.
The one thing I know for certain, carpel tunnel is not the only pinch point for nerves into your arms. So it is too easy for GPs to say that and tell you tro get a splint for £8 from amazon to try it out. This is a delaying tactic and in no whay diagnoses anything. I know there are three pinch points to the arms. Shoulder, elbow and wrist. Ovbvious that means three different potential causes. Add on the fact that the issue could also be in the back where nerves leave the spine to the arms. Or the neck too.
Your GP will give you the test I said above. If nothing happens he/she will most likely ignore that and tell you to sleep with a wrist splint. If you want to cut the time taken to get a proper diagnosis then buy one for each hand for about £8 each on amazon then wear them in bed for a few weeks at least before seeing your GP. When he/she says carpel tunnel you tell him/her that the carpel tunnel splints made no difference and you get the first stage out of the way quicker.
Just an idea based on my experience. In the meantime buy a £60, side sleeper pillow and you might not even need to bother the GP. I suppose if the pillow works it might indicate a shoulder or neck issue but I am no expert only know what helped me. I have not got it sorted out yet but at least I only have the odd bad night now not every night.
HTH