 Each symptom is a node, and a change in a node changes the probability distribution of the other symptoms which are connected to the original node. For example, difficulties in sleeping is likely to be strongly connected to fatigue, and both nodes may be connected to depressed mood, indicating that tired, sleep-deprived people are more likely to feel down and feel bad about themselves. (The connections could run in the other direction too, from low mood to difficulty sleeping.) Eventually we see a set of connections stabilizing the network as the symptoms of depression switch each other on and even symptom nodes that are not directly connected influence each other via shared neighbours (Borsboom 2017, p.6).