Sleep is essential for human beings to live a healthy life and to build a healthy society. However, there are few efficient drugs or treatments for sleep disorders since the detailed neuronal mechanisms associated with sleep are unknown. In particular, monophasic sleep at night as human is less understood due to a lack of model organisms. For example, most rodents used for life science research are nocturnal and take a polyphasic sleep.
Recently, we introduced a reptile, Australian bearded dragon Pogona vitticeps as a new model organism for sleep research. Pogona is diurnal and takes a monophasic sleep at night with periodic slow wave sleep (SWS) and REM sleep alternation. Furthermore, electrophysiological experiments and pharmacological treatment can be applied without much difficulty as in rodents. It may be suitable for sleep research, however, the basic properties of sleep in Pogona remain elusive. In this study, we examined whether sleep homeostasis is observed in response to sleep deprivation (SD). 7 hours of SD by light and gentle handling at night showed delayed wake-up time compared with a control group, suggesting the presence of sleep homeostasis in Pogona. Furthermore, LFP analysis showed that SD affected the periodic oscillation of SWS and REM sleep, as in humans. 
These results indicate that the features of sleep, especially sleep homeostasis in each sleep stage are similar between reptiles and mammals. Observation/manipulation of reptilian sleep may open a new avenue for understanding the fundamental functions and circuit mechanisms of monophasic sleep.