The Sleep Nullifying Apparatus: A Highly Efficient Method of Sleep Depriving Drosophila

Summary

Sleep deprivation is a powerful tool to investigate sleep function and regulation. We describe a protocol to sleep deprive Drosophila using the Sleep Nullifying Apparatus, and to determine the extent of rebound sleep induced by deprivation.

Abstract

Sleep homeostasis, the increase in sleep observed following sleep loss, is one of the defining criteria used to identify sleep throughout the animal kingdom. As a consequence, sleep deprivation and sleep restriction are powerful tools that are commonly used to provide insight into sleep function. Nonetheless, sleep deprivation experiments are inherently problematic in that the deprivation stimulus itself may be the cause of observed changes in physiology and behavior. Accordingly, successful sleep deprivation techniques should keep animals awake and, ideally, result in a robust sleep rebound without also inducing a large number of unintended consequences. Here, we describe a sleep deprivation technique for Drosophila melanogaster. The Sleep Nullifying Apparatus (SNAP) administers a stimulus every 10s to induce negative geotaxis. Although the stimulus is predictable, the SNAP effectively prevents >95% of nighttime sleep even in flies with high sleep drive. Importantly, the subsequent homeostatic response is very similar to that achieved using hand-deprivation. The timing and spacing of the stimuli can be modified to minimize sleep loss and thus examine non-specific effects of the stimulus on physiology and behavior. The SNAP can also be used for sleep restriction and to assess arousal thresholds. The SNAP is a powerful sleep disruption technique that can be used to better understand sleep function.

Introduction

Sleep is near universal in animals, yet its function remains unclear. Sleep homeostasis, the compensatory increase in sleep following sleep deprivation, is a defining property of sleep, that has been used to characterize sleep states in a number of animals^1,2,3,4,5.

Sleep in the fly has many similarities with human sleep, including a robust homeostatic response to sleep loss^4,5. Numerous studies of sleep in the fly have u....

Protocol

1. Experimental preparation

1. Collect flies as they eclose into vials, separating male and female flies.
   NOTE: Sleep experiments are commonly conducted with female flies. It is important to collect virgin females. Mated females will lay eggs that hatch into larvae complicating the analysis of the data.
2. House flies of a single sex in groups of <20.
   NOTE: Housing flies in a socially enriched environment (groups of >50) modulates sleep drive^6,13 potentially confounding measurements of rebound sleep. Further, following social enrichment, sleep will decline over a few days<....

Results

Canton S (Cs) was used as a wild-type strain. Flies were maintained on a 12 h light: 12 h dark schedule, and sleep deprived for 12 hours overnight. Inspection of the sleep profiles of Cs flies on the baseline day (bs), sleep deprivation day (sd), and two recovery days (rec1 and rec2) (Figure 2A) suggests that flies were effectively sleep deprived in the SNAP, and recovered sleep during the day consistent with observed reports in the literature

Discussion

Sleep in Drosophila was independently characterized in 2000, by two groups^4,5. In these pioneering studies, flies were deprived of sleep by gentle handling (i.e., hand deprivation) and shown to exhibit a robust homeostatic response to overnight sleep deprivation. Importantly, with any sleep deprivation experiment it is crucial to control for potential confounding effects of the method used to keep the animal awake. Hand deprivation studies set the benchm.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Locomotor activity tubes
Fisher Tissue Prep Wax	Thermo Fisher	13404-122	Wax used for sealing tubes
Glass tubes	Wale Apparatus	244050	We cut 5mm diameter Pyrex glass tubes into 65mm long tubes to record sleep. Pre-cut tubes can also be purchased.
Nutri Fly Bloomington Formulation fly food	Genesee Scientific	66-113	Labs might use their own fly food recipe. It is important that sleep be recorded on the same food that flies were reared in.
Rotary glass cutting tool	Dremel Multi Pro	395	Used to cut 65mm long glass tubes
Monitoring Sleep
DAM System and DAMFileScan software	Trikinetics		Software used to acquire data from DAM monitors and save the acquired data in an appropriate format
Data acquisition computer	Lenovo	Idea Centre AIO3	A equivalent computer from any manufacturer can substitute
Drosophila Activity Monitors	Trikinetics	DAM2	These monitors are used to record flies' locomotor activity
Environment Monitor	Trikinetics	DEnM	Not essential, but an easy way to monitor environmental conditions in the chamber where sleep is recorded
Light Controller	Trikinetics	LC4	A convenient way to control the timing of when the SNAP is turned on and off
Power Supply Interface Unit for DAM	Trikinetics	PSIU-9	Required for data acquisition computers to record Trikinetics locomotor acitvity data
RJ11 connector	7001-64PC	Multicomp	DAM monitors accept RJ11 jacks
Splitters	Trikinetics	SPLT5	Used to connect upto 5 DAM monitors
Telephone cable wire	Radioshack	278-367	Phone cables to acquire data from DAM monitors
Sleep Deprivation
Power supply	Gw INSTEK	GPS-30300	Power supply for the SNAP
Sleep Nullifying Apparatus	Washington University School of Medicine machine shop