I have no recollection of what happened just before I fell asleep last night because I had amnesia from the sleeping pills I took.
I don't remember what happened during the night because the medicine I took to help me sleep makes me forgetful.
ーI have no recollection of what happened just before I fell asleep last night because I had amnesia from the sleeping pills I took.
「飲んだ睡眠薬で健忘症になって、昨夜寝る前のことを記憶していない。」
have no recollection of ... で「…を覚えていない・記憶していない」
fall asleep で「寝入る・眠りにつく」
amnesia で「健忘症」
sleeping pills で「睡眠薬」
ーI don't remember what happened during the night because the medicine I took to help me sleep makes me forgetful.
「睡眠薬のせいで忘れっぽくなって、夜間に起こったことを覚えていない。」
during the night で「夜間に」
medicine I took to help me sleep で「眠るのを助けるために飲んだ薬」＝「睡眠薬」
forgetful で「忘れっぽい」
ご参考まで！
カナダ 
