Unlike an ache or pain that's there one minute and gone the next, stomach cramps are characterised by sudden, involuntary tightening of the tummy muscles - or spasms - that are more intense and cyclic. These cramps can be uncomfortable and may be accompanied by other digestive symptoms, such as bloating, nausea, vomiting, or diarrhoea.
This is a companion discussion topic for the original article at https://patient.info/news-and-features/what-causes-nighttime-stomach-cramps