downer

noun
1
a drug, especially a barbiturate, that relaxes you or makes you want to sleep
داروی آرام‌بخش, داروی خواب‌آور
compare upper
2
an experience that makes you feel sad or depressed
تجربه نااُمیدکننده, اتفاق ناراحت‌کننده, احساس افسردگی آور
Not getting the promotion was a real downer.
He's really on a downer .