A sleep aid system 1 for an infant comprising: an inflatable pad 2 for supporting the infant, pad 2 being compressible under load and resiliently returnable to an expanded shape when unloaded； a reservoir in fluid communication with pad 2 forming an enclosed fluid system so that when the reservoir contracts, fluid is transferred from the reservoir to the pad 2； a breathing emulation mechanism to contract and expand the reservoir； and a valve. The valve allows air to exit the fluid system to atmosphere when the fluid system’s interior pressure exceeds a first predetermined threshold, and further allows ambient air from atmosphere to enter the fluid system when the fluid system’s interior pressure is below a second predetermined threshold, the first predetermined threshold being higher than the second predetermined threshold. Preferably, system 1 comprises a control module 4 that houses the reservoir and breathing-emulation-mechanism separate from pad 2. System 1 may comprise a controller to control the frequency of reservoir contraction and expansion to emulate breathing. The reservoir may comprise a flexible bladder or a bellows, where the breathing emulation mechanism comprises a motor for reservoir compression. Pad 2 may comprise a resilient insert to cause its return to the expanded state when unloaded.
