How to get nice waves with no heat?

how can i style my hair over nighy to have nice waves / curls / somekindofnicetexture over night ? my hair natural has somewhat ringlets from the ears down and come about 3 - 4 inches below my shoulders . my natural texture doesn't stay in over night and i don't have time to shower and style in the am . i don't have a diffuser /: and i want to stay away from heat except maye blowdrying . thanks !