As '共' (Tomo) of Manyogana (early Japanese syllabary composed of Chinese characters used phonetically) has never been used as conjunctions of 'domo' and 'tomo' indicating fixed conditions of paradox, both of the above reading have been interpreted as 'sleep together.'
ただ、万葉仮名の「共」を逆説の確定条件を示す接続助詞「ども」や「とも」として用いる例はないので、上のいずれの読み方であっても「ともに寝る」という解釈がされている。