A deep sleep stage in Drosophila with a functional role in waste clearance

Bart Van Alphen, Evan R. Semenza, Melvyn Yap, Bruno Van Swinderen, Ravi Allada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Sleep is a highly conserved state, suggesting that sleep's benefits outweigh the increased vulnerability it brings. Yet, little is known about how sleep fulfills its functions. Here, we used video tracking in tethered flies to identify a discrete deep sleep stage in Drosophila, termed proboscis extension sleep, that is defined by repeated stereotyped proboscis extensions and retractions. Proboscis extension sleep is accompanied by highly elevated arousal thresholds and decreased brain activity, indicative of a deep sleep state. Preventing proboscis extensions increases injury-related mortality and reduces waste clearance. Sleep deprivation reduces waste clearance and during subsequent rebound sleep, sleep, proboscis extensions, and waste clearance are increased. Together, these results provide evidence of a discrete deep sleep stage that is linked to a specific function and suggest that waste clearance is a core and ancient function of deep sleep.

Original languageEnglish (US)
Article numbereabc2999
JournalScience Advances
Issue number4
StatePublished - Jan 20 2021

ASJC Scopus subject areas

  • General


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