Hello and welcome to health care magic, Although theoretically I can think of many reasons why a nightmare can elicit a nose bleed like elevated blood pressure or trauma or just increased blood flow and congestion, I would not assume a direct connection. Your partner may have nose bleed even otherwise and the nightmare could just make him get up and realize that. In any case you need to take a complete blood testing including coagulation profile and also a CT PNS and also nasal endoscopy and get back to me or any ENT with the reports as soon as possible. You need to also consult a psychiatrist so that a proper reason why your partner is getting frequent nightmares can be found out Get his pressure under control as increased tension or pressure can cause nose bleed which is the body s way of letting out the steam so to speak Hope this helps regards Dr Sriram nathan