What Could Be The Cause A Temporary Vision Of A Slight Greenish Patch For A Few Seconds Upon Waking Up?

Hello, when i wake up, i see a slight greensih patch. there is a white clock besides where i sleep, i noticed this beacuse the clock appears a bit greenish or corroded (like a old building with fungus etc. ) This appears for 3-4 secondfs when i am about to get up and then nothing. I have BP, metropolol 50 since 7 years , glasses with -0.75 number and on anti anxiety meds.