The medical term for your finger(s) locking up at night is 'trigger finger', it is a common sympton associated with people who suffer from arthritus. It can also be caused through applying excessive strain on the fingers and wrists, i.e. using heavy WFPoles for prolonged periods. How do I know this; because I have chronic arthritus and have to take up to 26 tablets daily. I diet carefully, rest and relax when my body is feeling tired and exhausted instead of continuing to work and antagonising the arthritus flare ups. One major help I've found is to use the lightest, sturdiest WFPoles I can possibly use. This has made a very big difference to my health and my arthritus is showing very good signs of vastly improving. I use microbore hose to cut down on the strain on my hands and have almost given up all my WFP trolley and ladder work now. I WFP and leave the brush on the glass when rinsing instead of trying to lift the brush off. Basically, I try to make my life as simple as possible and try to pick up the biggest and easiest WFP jobs in my area that are hassle free.