Fig. 1.

Small animal models of sleep research. This unrooted, pruned cladogram is inclusive of animals that have been established as models for studying sleep, demonstrating the diversity of sleep behaviors throughout the animal kingdom. Branches demonstrate broad relationships among animals, but do not represent actual distance measures. Taxonomic information was obtained from the NCBI Taxonomy Database and the tree generated with NCBI Common Tree (Sayers et al., 2012). The circular cladogram was generated using the Interactive Tree of Life (Letunic and Bork, 2016) and estimates of divergence were derived from the TimeTree Database (Hedges et al., 2015). mya, million years ago.