We developed a natural sleep restriction method for zebra fish larvae: swimming against flowing water.
Using the water flow method, we sleep deprived the larvae, and measured their reactivity for stimulation.
The larvae exhibit a standard response to novel stimulation: startle reflex. The reflex consists of two main parts: short and long latency responses. The responses of 20-30 larvae were simultaneously imaged and analyzed during spontaneus swimming period at different times of the day and after the forced awimming period.
After a long swim period, the stimulation threshold was increased, meaning that fewer larvae exhibited the startle reflex response. Increased treshold to react for stimulation is one of the core features of sleep homeostasis in all species.
This showed, for the first time convincingly, that these larvae have similar regulation of sleep homeostasis as other species, and they can thus be used as model animals for sleep research.