1. A recent study in PNAS claims that exposure to orange light could have an impact on cognitive function. The MRI results certainly appear significant but I'm not familiar enough with the field to know if they're reliable. Caveats: Their sample size was 16 people, the effects of the particular light were noticeable more than an hour post-exposure, and potential participant effects (i.e., how sleepy they felt) were all self-reported, though the researchers state these reports were consistent. I'm curious to see if the results can be replicated with a different sample of volunteers. (The paper by Chellapa et al. is here.)
2. C. elegans glows blue when it dies. Don't take my word for it. Take the word of Coburn et al. from their 2013 PLoS Biology paper, Anthranilate Fluorescence Marks a Calcium-Propagated Necrotic Wave That Promotes Organismal Death in C. elegans: "We report that organismal death is accompanied by a burst of intense blue fluorescence, generated within intestinal cells by the necrotic cell death pathway." It turns out that, at least in C. elegans, organismal death looks like a wave of necrosis as a cascade of self-destruction propagates cell death. The short story: cells burst, pH increases, things that wouldn't normally be fluorescent suddenly are. The death-glow may have been found to happen in yeast, too (Coburn et al. cite this 2007 paper by Liang et al but I couldn't find any explicit mention in it about blue fluorescence, just yellow and red).