2.5 Restraint Stress

Stressed group rats were restrained in their home cages using Rat Snuggles (Harvard Apparatus) for 3 h immediately preceding the probe trial (12PM – 3PM). They were continuously monitored for the duration of the restraint and their vocalizations and struggles were noted and analyzed to construct an index of apparent distress (the number of times each rat squawked or struggled to get out of the restraint was tallied for each hour of the stress period). Control animals remained in the housing facility during the stress period and joined the stressed group at the beginning of the probe trial. Animals were returned to the housing facility at the conclusion of the probe trial for sleep data collection during the ensuing 12 hour inactive period.