We also performed high resolution video recordings of commonly used drivers in the fly sleep field. Optogenetic activation of these drivers do not promote HS. However, we observed micromovements with the widely used driver R23E10 (an observation that was previously made by French et al., 2021)

In some cases, flies were unable to maintain normal posture which can be seen below.

We also tested the sleep inducing drug gaboxadol. Flies fed with gaboxadol had impaired locomotion and exhibited repeated proboscis extension behavior.

Flies were harder to arouse after HS suggesting that HS marks a distinct state. Furthermore, similar to how we open our eyes when we wake up, flies exhibited reversal of sleep related behaviors. Reverse HS prior to wakefulness followed by lifting of the antenna.

We looked at flies close, very close, to see if there are any subtle behaviors that might indicate their internal state (i.e. sleep). In addition to previously observed behaviors, we identified a novel one which we call "haltere switch" (HS).