everybody dreams every night, it's part of a normal deep sleep pattern. However most people forget their dreams as they move onto a different part of their sleep pattern. Physiological changes such as pregnancy can change your sleep patterns and make you remember your dreams, but so can external factors such as stress or a change in routine (sleeping at a different time of day and awaking early to unusual noises, new heating systems, etc).

The other reason I believe that people start to remember their dreams, or have more vivid dreams, is that there is a message in the dream for them or for someone else. Like you I usually remember my dreams but sometimes they stick in my mind more that others and sometimes there seems to be a message or importance in that dream. Could there be a message in your dreams?