“与某人同眠共枕”常见的英文表达有 “share a bed with someone” 或者 “sleep in the same bed as someone”。
例如：
She has been sharing a bed with her husband for years.（她已经和丈夫同眠共枕多年了。）
I used to sleep in the same bed as my sister when I was a kid.（我小时候常和妹妹同眠共枕。）