Biology
The Neurobiology of Circadian Rhythms and Activity Patterns in Fruit Flies
Quick fact
Fruit flies have about 150 dedicated clock neurons in their brains; mutations in the 'period' gene can make them run on a 19-hour day or even be completely arrhythmic.
Why this is interesting
Fruit flies are tiny, but they wake and sleep on a precise 24-hour schedule—just like you. How does a fly's brain keep track of time?