Response to commentary "Hypnotic-associated falls across the diurnal cycle: Pharmacokinetic signal or delirium rhythm?".

Social insects demonstrate remarkable collective behaviours and provide powerful systems for understanding how complex group-level organisation can emerge from simple local interactions. Construction, decision making and foraging organisation can emerge from self-organising principles (; ; ; ; ), where global pattern and order emerge from interactions among lower-level components of the system. In social insect colonies, individuals follow behavioural rules utilising local information available to them, which emergently leads to collective behaviour (; ). One fascinating large-scale collective behaviour is nest construction, where colonies of social insects create and maintain large, complex structures without top-down organisation (; ; ; ; , ). Nest construction also involves smaller scale collective behaviours whereby groups of workers move pieces of nest material together (). This so-called cooperative transport (; ; ; ) is a cooperative behaviour that benefits individuals () by enabling a task to be performed more efficiently. While individuals gain short-term advantages by sharing the load, it ultimately supports overall colony performance. Cooperative transport, defined as two or more individuals moving an item simultaneously, is common in ants and has been recorded in at least 40 genera (; ; ). It typically involves transporting food to the nest (; ; ; ). In contrast, cooperative transport during nest construction or maintenance is poorly understood, despite occasional reports of workers moving nest material () or brood (). Collaborative transport occurs on a continuum from highly organised with coordination rules and task separation, through to poorly organised behaviours where multiple individuals try to move an object together in an uncoordinated way (reviewed in ; ), resulting in deadlocks and movement inefficiencies (; ; ).