YOU SAID:

I've been sleeping in the same bed for millenia

INTO JAPANESE

私は何千年も同じベッドで寝ています

BACK INTO ENGLISH

I have been sleeping on the same bed for thousands of years

INTO JAPANESE

私は何千年もの間同じベッドで寝ています

BACK INTO ENGLISH

I have been sleeping in the same bed for thousands of years

INTO JAPANESE

私は何千年も同じベッドで寝ています

BACK INTO ENGLISH

I have been sleeping on the same bed for thousands of years

INTO JAPANESE

私は何千年もの間同じベッドで寝ています

BACK INTO ENGLISH

I have been sleeping in the same bed for thousands of years