A cell, which is more negatively charged than at rest, is hyperpolarized.
A cell is hyperpolarized when a change in the cell’s membrane potential (the difference in electric potential between the inner and the outer area of a biological cell) makes it more negative at a certain spot on the cell’s membrane. Hyperpolarization of a cell occurs when ion channels in the membrane open which allows positive ions to flow out of the cell or negative ions to flow inside the cell. This condition in excitable cells such as muscle and neuron cells is likely to make the cells less reactive to impulses.