My smoke detectors keep going off in the middle of the night?

In order of frequency, smoke detectors sound off because of: low battery (usually just a chirp); smoke from something burning in the kitchen or actual fire (full alarm until air clears); dust or debris (maybe a bug) accumulated (full alarm, sometimes this can be intermittent or incomplete); internal failure of components (need to replace fire alarms every 5 years); loose connection (wire slips loose from the "wire nut" connector somewhere in the circuit if it is connected to a house system or powered by house circuit). Start by replacing batteries. Replace your detectors if they are over five years old. If the false alarm persists, check wire connections by dropping detectors and tugging on each wire individually to ensure connection.