Similar for me, working as a engineering consultant for the pharma industry. Some clients test more than others. We have terminated guys for a failed test. Especially since they had been told what client they were being hired for and that they WILL be tested. My current client doesn't test that I know of. Might be partly because they are European based and maybe partly because we are 12 miles from MA where it's been legal for years and where a large number of employees reside. Alcohol is tested as well, although in that case I believe there is an allowed amount.
But since I never know if or when I might get assigned to a project for a client that tests...
As far as the sleep thing... I've tried all sorts of things... no drinking (helps some, but not always), no phone (same), reading (helps some), listening to audio books (actually helps quite a bit). I definitely need fairly heavy covers although a weighted blanket is too much.