A two-process model of Drosophila sleep reveals an inter-dependence between circadian clock speed and the rate of sleep pressure decay.

Sleep is controlled by two processes-a circadian clock that regulates its timing and a homeostat that regulates the drive to sleep. Drosophila has been an insightful model for understanding both processes. For four decades, Borbély and Daan's two-process model has provided a powerful framework for understanding sleep regulation.

Homeostatic control of deep sleep and molecular correlates of sleep pressure in .

Homeostatic control of sleep is typically addressed through mechanical stimulation-induced forced wakefulness and the measurement of subsequent increases in sleep. A major confound attends this approach: biological responses to deprivation may reflect a direct response to the mechanical insult rather than to the loss of sleep. Similar confounds accompany all forms of sleep deprivation and represent a major challenge to the field.

Parametric effects of light acting via multiple photoreceptors contribute to circadian entrainment in .

Circadian rhythms in physiology and behaviour have near 24 h periodicities that must adjust to the exact 24 h geophysical cycles on earth to ensure adaptive daily timing. Such adjustment is called entrainment. One major mode of entrainment is via the continuous modulation of circadian period by the prolonged presence of light.

PHASE: An Open-Source Program for the Analysis of ase, ctivity, and leep Under ntrainment.

The problem of entrainment is central to circadian biology. In this regard, has been an important model system. Owing to the simplicity of its nervous system and the availability of powerful genetic tools, the system has shed significant light on the molecular and neural underpinnings of entrainment.

Responses of activity rhythms to temperature cues evolve in populations selected for divergent timing of eclosion.

Even though the rhythms in adult emergence and locomotor activity are two different phenomena that occur at distinct life stages of the fly life cycle, previous studies have hinted at similarities in certain aspects of the organisation of the circadian clock driving these two rhythms. For instance, the gene plays an important regulatory role in both rhythms. In an earlier study, we have shown that selection on timing of adult emergence behaviour in populations of leads to the co-evolution of temperature sensitivity of circadian clocks driving eclosion.