Stress-induced changes in sleep in rodents: Models and mechanisms

Abstract

Psychological stressors have a prominent effect on sleep in general, and rapid eye movement (REM) sleep in particular. Disruptions in sleep are a prominent feature, and potentially even the hallmark, of posttraumatic stress disorder (PTSD) (Ross, R.J., Ball, W.A., Sullivan, K., Caroff, S., 1989. Sleep disturbance as the hallmark of posttraumatic stress disorder. American Journal of Psychiatry 146, 697-707). Animal models are critical in understanding both the causes and potential treatments of psychiatric disorders. The current review describes a number of studies that have focused on the impact of stress on sleep in rodent models. The studies are also in Table 1, summarizing the effects of stress in 4-h blocks in both the light and dark phases. Although mild stress procedures have sometimes produced increases in REM sleep, more intense stressors appear to model the human condition by leading to disruptions in sleep, particularly REM sleep. We also discuss work conducted by our group and others looking at conditioning as a factor in the temporal extension of stress-related sleep disruptions. Finally, we attempt to describe the probable neural mechanisms of the sleep disruptions. A complete understanding of the neural correlates of stress-induced sleep alterations may lead to novel treatments for a variety of debilitating sleep disorders.

Behavioral and biochemical dissociation of arousal and homeostatic sleep need influenced by prior wakeful experience in mice

“…Although GH is widely used for SD studies, the details vary according to the protocol adopted (3,4,8,9). In this study, we specifically avoided the use of novel objects or other methods that might elicit emotional stimuli, locomotion, or voluntary arousal in the GH group (19).…”

“…During GH SD, we continuously observed the behavior of each mouse and touched or tapped the cage gently to disturb them if they adopted a presleep posture such as starting to recline or lowering their heads to the floor of the cage. For the voluntary awake model, we performed cage changes once an hour to keep the mice awake by using their instinctive, spontaneous exploration of novel environments (4). Although a single cage change has been shown to keep mice awake for about 1.5-2.0 h (4), we also visually monitored the CC group throughout the 6-h SD period.…”

0075 Nitrergic Neurons of the Dorsal Raphe Nucleus Encode Information About Stress Duration

“…Evidence shows that duration of restraint stress has a direct effect on rapid eye movement (REM) and non-rapid eye movement (NREM) types of sleep [17]. For instance, 0.5 hours of restraint showed increases in both REM and NREM while 4 hours of restraint showed no changes in either REM or NREM [17].…”

“…Duration and modality are important variables to consider when discussing the response to stress. Duration especially has been shown to have different effects on behavioral paradigms such as sleep [17]. Duration of acute stress also effects facilitation of the HPA axis where duration effects the intensity [15].…”

Translational Models of Sleep and Sleep Disorders

“…The mechanisms by which stress contributes to persistent insomnia remain unclear, although the principles of allostatic sleep modifi cation have the most circumstantial support. Stress effects on rodent sleep were recently reviewed by Pawlyk et al 326 comparing sleep effects across stress methods and strains. Stress intensity, estimated by measuring plasma cortisol or epinephrine levels after the stressor, tends to increase sleep at low levels and to decrease sleep at high levels.…”