Introduction: 280 million adults have been diagnosed with depression worldwide, of which, more than 90% of people encounter sleep disorders (WHO, 2023; Wang et al., 2015). The consequences of persistent poor sleep quality are detrimental, resulting in cognitive impairments, emotional instability, a predisposition to cardiovascular, musculoskeletal, and neurological disorders, or early death (Joiner, 2016). Reflected in internationally recognised guidelines, selective serotonin reuptake inhibitors (SSRIs) are the most common antidepressants prescribed in England, responsible for suppression of rapid eye movement (REM) sleep as well as sleep fragmentation (Wang et al., 2015; Hutka et al., 2021). The aim of this research is to further explore the effects of antidepressants on sleep, with the intention of investigating whether the wake-promoting effects of SSRI, fluoxetine, will disrupt sleep behaviours in S. gregaria.
Methods: A mixed-methods approach was chosen for data collection, comprising of behavioural observations over a duration of 48 hours, followed by quantitative analysis of the locust samples using gas chromatography/mass spectrometry (GC/MS).
Results: Velocity, distance travelled and jumping activity were measured in the locusts. Locomotion was notably reduced in the 20mg and 40mg fluoxetine groups, and no signs or aggression or cannibalistic behaviours were observed in either control or experimental groups. Detection of serotonin and melatonin concentrations in the locust samples were inconclusive and require further study.
Discussion: The results suggest fluoxetine interrupted locust behaviour, the locusts in the 20mg and 40mg pools appeared sluggish, they were slow to react and presented with a decline in exploratory behaviours – all suspected to be a consequence of sleep deprivation in the locusts, which may be comparative to mammals. Despite the promising findings, further research is needed to explore S. gregaria as an invertebrate model to tentatively model the effects of antidepressants on sleep in humans.
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