When do cavities form? do they only form when you're asleep, do they form when you're awake?

24/7/365: Cavities form when acid which is released by the bacteria stuck to your teeth dissolves the mineral matrix of the enamel. This can happen at any time, but it's more of a problem at night, when you're asleep. Decreased salivary flow and formation of colonies only exacerbates the problem. Keep your teeth clean by flossing and brushing to help minimize decay formation.

Any time: Food (sugar) + bacteria-> produces acid= cavities form. You can't eliminate the ever-present bacteria in your mouth and therefore whenever you have food\food debris as an energy source, acid is produces and cavities form. The better you brush and floss and avoid foods that contribute to dental decay, the less cavities you get. Day, night, anytime. Overnight with less salivary flow, it's worse.