When people want stress relief, they tend to go for massage-the manipulation of muscles, the prone sleeping position and the feel of another's hands all create a comforting environment.

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The proposed sleeping position involves leaning forward and placing your head on the pillow's sloped top.

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Dr Drucker, whose has also examined why smoking and sleeping position are risk factors for SIDS, says this latest research will help establish the cause of death in certain cases.

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Each sleep position has benefits and disadvantages, although sleeping on the stomach generally isn't recommended because it can constrain the neck.

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This experiment does, however, suggest that genetics alone may explain some cases of SIDS. In the past, explanations have concentrated on environmental factors such as the smoking habits of the parents, bacterial infection and (most famously) a baby's sleeping position.

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