The present invention is directed to a method of continuously monitoring neuronal avalanches in a subject comprising (a) determining a deviation in avalanche exponent (α) or branching parameter (σ) from a predetermined value at rest, wherein the pre-determined value of α is a slope of a size distribution of the synchronized neuronal activity and the predetermined value is −3/2 and the pre-determined value of σ is a ratio of successively propagated synchronized neuronal activity and the predetermined value is 1； and (b) repeating step (a) one or more times to continuously monitor neuronal avalanches in a subject. The invention also features methods of determining or monitoring the degree of sleep deprivation in a subject, methods of identifying subjects that are susceptible to a sleep disorder and methods of diagnosing a sleep disorder in a subject.
