Well, actually you dream every night (studies have proven you would go clinically mad if you didn't dream every night) but you only remember one a week. They occur during REM sleep (Rapid Eye Movement) when your physical body is also regenerating. Dreams are the regeneration of your spiritual body.
Blood is usually bad in dreams (unless it is menstrual blood) as it is the draining of the life-force. A nose bleed relates to finances and is a warning to keep your money in order or you may get into financial problems in the next few months.
