This is difficult to answer. Some mild shaking upon waking is common in very young babies, but very unusual in a child of 21 months.It is sometimes a sign that a child has a full bladder and is passing urine. Your son's shaking may be normal but it occurs all the time and has been going on for a long time. It would be best to see your paediatrician about this as he/she may want to do some tests to exclude any thyroid problems and check his blood sugar level for a start.
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