Initial studies in the day active marmoset monkey (Callithrix jacchus) indicate that the sleep-wake cycle of these non-human primates resembles that of humans and therefore conceivably represent an appropriate model for human sleep. The methods currently employed for sleep studies in marmosets are limited. The objective of this study was to employ and validate the use of specific remote monitoring system technologies that enable accurate long-term recordings of sleep-wake rhythms and the closely related rhythms of core body temperature (CBT) and locomotor activity in unrestrained group-housed marmosets. Additionally, a pilot sleep deprivation (SD) study was performed to test the recording systems in an applied experimental setup. Our results show that marmosets typically exhibit a monophasic sleep pattern with cyclical alternations between NREM and REM sleep. CBT displays a pronounced daily rhythm and locomotor activity is primarily restricted to the light phase. SD caused an immediate increase in NREM sleep time and EEG slow-wave activity as well as a delayed REM sleep rebound that did not fully compensate for REM sleep that had been lost during SD. In conclusion, the combination of two innovative technical approaches allows for simultaneous measurements of CBT, sleep cycles and activity in multiple subjects. The employment of these systems represents a significant refinement in terms of animal welfare and will enable many future applications and longitudinal studies of circadian rhythms in marmosets.

The day-active tree shrew shares most of the characteristics of sleep structure and sleep homeostasis that have been reported for other mammalian species, with some peculiarities. Because the tree shrew is an established laboratory animal in neurobiological research, it may be a valuable model species for studies of sleep regulation and sleep function, with the added advantage that it is a day-active species closely related to primates.

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BACKGROUND: Lifelong consumption of a Western-style diet is a risk factor for developing metabolic disorders and therefore impairs healthy aging. Dietary restriction (DR) could delay the onset of age-related diseases and prolong life span, however, the extent to which this depends on diet type is poorly understood. OBJECTIVE: To study whether feeding a Western-style diet affects the healthy aging benefits of DR. METHODS: Mice fed a Western-style diet (ad libitum and DR) were compared to those fed a standard healthy diet (ad libitum and DR). Survival and several metabolic and endocrine parameters were analyzed. RESULTS: Lifelong consumption of a Western-style diet resulted in increased adiposity, elevated triglyceride levels in plasma, higher homeostatic model assessment-insulin resistance and higher resting metabolic rate in mice compared to the standard diet group. This was accompanied by reduced survival in the Western-style diet group. DR irrespective of diet type improved abovementioned parameters. CONCLUSIONS: Lifelong restricted consumption of Western-style diet led to improved metabolic and endocrine parameters, and increased survival compared to the ad libitum Western-style diet group. Interestingly, the survival was comparable in restricted Western-style and standard diet groups, suggesting that reduced food intake rather than diet composition play more important role in promoting longevity/survival.