I have really short eyelashes and they keep on falling out, tips?

basically my eyelashes are reaally short anyway and they're really fair aswell (odd considering i have very dark hair naturally) and they all keep on falling out, i really dont know why! its getting to the point where putting on mascara doesnt make a huge difference anymore.. so any tips on stopping them from falling out or reasons behind it?!? or alternatively any helpful products, like decent mascaras! thankyou :)