Keeping a dream journal, noting sleep times and dream recall, can be useful for exploring dreams.

“You know, there's not a lot of hard data about how to do this, but a lot of people report keeping a sleep journal, where a dream journal can be very useful. So they mark when they think they fell asleep the night before, when they woke up and if they wake up in the middle of the night, early in the morning they'll just write down what they can recall of their dreams. And even if they recall nothing, many people have the experience of mid morning or later afternoon that suddenly comes to them that they had a dream about something and writing that down.”