Sleeping mask med effect to people who sleep day time?

Whaaaa? Sleeping mask ensures dark environment for sleep, to eliminate major "zeitgeiber" (bringer of the day) that triggers brain to release "wake-up" hormones. Med effect from sleeping meds just sedates brain (/body) to make it easier to get to / stay asleep. Day sleepers average less total sleep & poorer health than "normal" folks, so help them out and let them sleep.