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We investigated whether nocturnal eating was causal to the impairment of metabolism and sleep disruption in diurnal animals exposed to illuminated nights. Adult zebra finches hatched and raised in 12 h light: 12 h darkness (LD) were exposed to 5-lux dim light at night (dLAN, two groups), with a control group maintained on LD. For the next 3 weeks, the food availability to one of the dLAN groups was restricted to the 12 h light period (dLAN -F); the other dLAN (dLAN +F) and LD groups were continued on ad lib feeding. In spite of similar food intakes, dLAN +F condition led to the fat accumulation and weight gain. These birds showed concurrent changes in hepatic expression of genes associated with carbohydrate and lipid metabolism, suggesting an enhanced gluconeogenesis and impaired fatty acids synthesis. Increased sirt1 mRNA levels indicated the activation of molecular mechanisms to counter-balance the metabolic damage under dLAN +F. Furthermore, reduced bout length and total duration of the nocturnal sleep suggested a poorer sleep in dLAN +F condition. Negative sleep effects of dLAN were supported by the lower hypothalamic expression of sleep promoting sik3 and camkii genes, and higher mRNA expression of awake promoting achm3 gene in dLAN +F, compared to the LD condition. Importantly, dLAN-induced negative effects in metabolism and sleep were alleviated in the dLAN -F group. These results suggest the role of timed feeding in alleviating the negative impact of illuminated nights in metabolism and sleep in diurnal zebra finches.

The ability to recognize oneself is separate from recognizing a conspecific. Self-recognition is a higher cognitive function and generally tested by a mirror-mark paradigm, in which the individual recognizes and responds to an inconspicuously placed mark on body from its mirror-reflected image. Although initially suggested to be associated with large-brained mammals, the ability of self-recognition has now been shown in non-mammals, including fish and birds. Hence, studies on many more species might be useful to understand general principles and underlying mechanisms of the evolution of social intelligence. Here, we examined self-recognition ability in Indian house crows (Corvus splendens), by testing them first for mirror-induced responses and then for the mark-directed responses. A circular coloured mark was inconspicuously placed on the throat under the bill where crows could see it only from its mirror-reflected image; a similar black mark placed at identical location which was difficult to be seen served as the control condition. We evaluated how closely crows viewed and inspected the object, and expressed social, contingent and self-directed responses to the mirror and cardboard. Crows exhibited greater preference in response to the mark when in front of the mirror, compared to they were in front of the non-reflective black cardboard. The majority (4/6) crows responded to the mirror-reflected self-image, as evidenced by attempts to remove the coloured mark by using beak or claws; no such response was found in control condition. These results suggest self-recognition by Indian house crows, and support the growing evidence that the ability of self-recognition is more widely present among animals.

This study investigated the role of nocturnal melatonin secretion in the cognitive performance of diurnal animals. An initial experiment measured the cognitive performance in Indian house crows treated for 11 days with 12 h light at 1.426 W/m