Enhanced brain small‐worldness after sleep deprivation: a compensatory effect

Sleep deprivation has a variable impact on extrinsic activities during multiple cognitive tasks, especially on mood and emotion processing. There is also a trait‐like individual vulnerability or compensatory effect in cognition. Previous studies have elucidated the altered functional connectivity after sleep deprivation. However, it remains unclear whether the small‐world properties of resting‐state network are sensitive to sleep deprivation. A small‐world network is a type of graph that combines a high local connectivity as well as a few long‐range connections, which ensures a higher information‐processing efficiency at a low cost. The complex network of the brain can be described as a small‐world network, in which a node is a brain region and an edge is present when there is a functional correlation between two nodes. Here, we investigated the topological properties of the human brain networks of 22 healthy subjects under sufficient sleep and sleep‐deprived conditions. Specifically, small‐worldness is utilized to quantify the small‐world property, by comparing the clustering coefficient and path length of a given network to an equivalent random network with same degree distribution. After sufficient sleep, the brain networks showed the property of small‐worldness. Compared with the resting state under sufficient sleep, the small‐world property was significantly enhanced in the sleep deprivation condition, suggesting a possible compensatory adaptation of the human brain. Specifically, the altered measurements were correlated with the neuroticism of subjects, indicating that individuals with low‐levels of neuroticism are more resilient to sleep deprivation.