A system in which a wearable device detects an electroencephalographic (EEG) response from a user during sleep-related activity, e.g. trying to fall asleep, being asleep or waking up, and outputs an audio signal that is tailored, based on the EEG response, to enhance the user's sleep experience. In particular, an audio, thermal and/or olfactory signal may be used to facilitate any one or more of (i) a smooth path into REM sleep, (ii) a reduced potential for sleep being disturbed, and (iii) exit from sleep at an optimum time. In one example, the system synchronizes properties of an audio signal comprising a dominant white and/or pink noise component with the identified sleep-related parameters. The synchronized properties can include any of intensity, frequency, tone, volume and rhythm.