Chronic mild stress affects sucrose intake and sleep in rats

Depression in humans is associated with sleep abnormalities of three types: altered rapid eye movement (REM) sleep, fragmented sleep, and reduced delta sleep. In an animal model of depression, chronic exposure to mild stressors (CMS, e.g. periods of soiled cage, reversed light/dark cycle, grouped housing, food and/or water deprivation) causes behavioral and hormonal changes which, […]

History and future of comparative analyses in sleep research

The comparative methods of evolutionary biology are a useful tool for investigating the functions of sleep. These techniques can help determine whether experimental results, derived from a single or few species, apply broadly across a specified group of animals. In this way, comparative analysis is a powerful complement to experimentation. The variation in the time […]

Avian sleep homeostasis: Convergent evolution of complex brains, cognition and sleep functions in mammals and birds

Birds are the only taxonomic group other than mammals that exhibit high-amplitude slow-waves in the electroencephalogram (EEG) during sleep. This defining feature of slow-wave sleep (SWS) apparently evolved independently inmammals and birds, as reptiles do not exhibit similar EEG activity during sleep. In mammals, the level of slow-wave activity (SWA) (low-frequency spectral power density) during […]

Sleep imaging and the neuropsychological assessment of dreams

Recent neuroimaging studies show that human rapid-eye-movement (REM) sleep is characterized by a specific pattern of regional brain activity. Although this is usually interpreted in relation to physiological and cellular mechanisms, the specific regional distribution of brain activity during REM sleep might also be linked to specific dream features. Remarkably, several bizarre features of normal […]

Sleep and Obesity: A Focus on Animal Models

The rapid rise in obesity prevalence in the modern world parallels a significant reduction in restorative sleep (Agras et al., 2004; Dixon et al., 2007, 2001; Gangwisch and Heymsfield, 2004; Gupta et al., 2002; Sekine et al., 2002; Vioque et al., 2000; Wolk et al., 2003). Reduced sleep time and quality increases the risk for […]

Agreement between different sleep states and behaviour indicators in dairy cows

Conclusive data regarding behavioural indicators of different sleep states in adult dairy cows are lacking, i.e. agreement between behavioural indicators of sleep and corresponding electrophysiological measures. Behavioural estimates for quantifying total sleep time in calves have been developed, so this study examined whether these behavioural estimates also apply for adult cows. Behaviour observations and electrophysiological […]