Is today the day we find out about the five accomplishments of the Sleep Ecophysiology Group to unfold in just the last ten days? … … Yes, it is. And so, with great admiration and pride, I introduce:
1. Omond SET, Hale MW and Lesku JA. 2022. Neurotransmitters of sleep and wakefulness in flatworms. Sleep 45, zsac053.
*It is my pleasure to share with you Shauni’s latest magnum opus, now online at Sleep. Shauni had already provided the first evidence for sleep (behaviour) in platyhelminth flatworms (Omond et al. 2017 Sleep). This alone was important given the paucity of comparative data on the mere presence of sleep outside of vertebrates, and a handful of arthropods, mollusks, and few others. Here, using a phenomenally impressive 504 flatworms, Shauni showed that the neurotransmitters dopamine and histamine are wake-promoting in flatworms (similar to flies, fishes and other vertebrates), whereas only GABA has a somnogenic role (similar to Hydra, flies, and vertebrates). She presents evidence that GABA could be the (evolutionarily) first neurotransmitter to regulate sleep. Next, Shauni will extend her behavioural and biochemical dissection of flatworm sleep to the electrophysiological.
2. Connelly F, Hall ML, Johnsson RD, Elliot-Kerr S, Dow BR, Lesku JA and Mulder RA. 2022. Urban noise does not affect cognitive performance in wild Australian magpies. Animal Behaviour, in press.
*Dr Connelly had another publication accepted from his PhD following his hits in Environmental Pollution and Current Biology. Here, Farley compared the cognitive performance of wild magpies exposed to differing levels of urban noise. Despite sleep-disrupting effects of urban noise (Connelly et al. 2020 Env Poll), Farley found no evidence that cognitive performance co-varied with the level of anthropogenic noise across an urban gradient of noise levels. Thus, fortunately, anthropogenic noise does not appear to negatively impact cognitive performance in these urban birds.
3. Russo AM, Payet JM, Kent S, Lesku JA, Lowry CA and Hale MW. 2022. Acute treatment with 5- hydroxytryptophan increases social approach behaviour but does not activate serotonergic neurons in the dorsal raphe nucleus in juvenile male BALB/c mice: a model of human disorders with deficits of sociability. Journal of Psychopharmacology, in press.
*With his second publication this week, Adrian is nearly a newly minted Doctor with that new-Doctor smell. Adrian’s forte focusses on the role of 5-HTP (a serotonin precursor) on mouse behaviour and neurophysiology. Why? A common laboratory mouse strain, BALB/c, has been proposed as a model of human sociability disorders, including autism spectrum disorders. Young BALB/c mice are anxious, anti-social and have reduced brain serotonin synthesis compared to other mouse strains. By treating mice with 5-HTP and augmenting brain serotonin levels, Adrian is able to make the anti-social – social! By increasing serotonin synthesis, he increases social behaviour, suggesting that serotonin synthesis may reduce anxiety and alleviate human sociability disorders.
4. Kelly ML, Collins SP, Lesku JA, Hemmi JM, Collin SP and Radford CA. 2022. Energy conservation characterizes sleep in sharks. Biology Letters 18, 20210259.
*Mike finished his PhD after having reviewed evidence for sleep in sharks (2019), demonstrating exciting diversity in the activity rhythms displayed by sharks (2020), and providing tantalizing evidence that restful sharks are sleeping sharks owing to increased arousal thresholds (2021). In the latter, however, he found no evidence that the sleep state was regulated as sharks forced to swim were not more inactive when allowed to behave freely. Hmm, was his thinking. And so, Mike teamed up with metabolical masterminds in NZ to measure oxygen consumption in draughtsboard sharks. Overall he found that sharks inactive for five minutes had lower metabolic rate and typically adopted a flat body posture; eye closure appeared to poorly reflect sleep. As a result, the conservation of energy appears to be a sleep function (or at least, a consequence) in quiescent sharks. You can hear more about this research, here.
5. Lesku JA and Schmidt MH. 2022. Energetic costs and benefits of sleep. Current Biology, in press.
*In this review, Markus Schmidt and I discuss the energy conservation role of sleep. Sadly, we did so too early to discuss sharks per se, but we were able to talk about garden warblers that save energy sleeping during stop-overs on long-distance migrations, and animals that accept the significant energetic costs to sustained wakefulness and sleep extremely little. We then evaluate three energetically-oriented hypotheses for the function of sleep, including energy conservation, adaptive inactivity, and energy reallocation and find that sleep-wake cycling may have evolved to optimize (rather than conserve) energy reserves.
And while we are at it, I think I missed broadcasting these two others papers from January –
6. Johnsson RD, Connelly F, Vyssotski AL, Roth TC and Lesku JA. 2022. Homeostatic regulation of NREM sleep, but not REM sleep, in Australian magpies. Sleep 45, zsab218.
*As hinted at above, sleep is regulated. You lose sleep, you sleep more to recover that lost sleep. After two papers suggesting that REM sleep was not regulated in magpies (Aulsebrook et al. 2020 Curr Biol; Connelly et al. 2020 Env Poll), Robin and I scratched our heads and thought to tackle the question outright using two durations of night-time sleep loss using a more direct method of sleep deprivation. Here, Robin manipulated the sleep-wake history of magpies: magpies experienced either a full 12-h night awake, or the first 6-h half of the night awake, which were preceded by a 36-h baseline recording and followed by a 24-h recovery period. As expected, Robin’s magpies recovered lost NREM sleep by sleeping more, with increased NREM sleep consolidation, and increased NREM sleep intensity during recovery sleep. For the first time, Robin showed that birds, like humans, show reduced NREM sleep intensity at night following daytime napping, indicating that sleep intensity reflects sleep need or pressure in birds. Unexpectedly however, the magpies did not recover any lost REM sleep. Why? We don’t know. The absence of REM sleep homeostasis has been reported in several bird and mammal species over the last couple years to unknown reason or significance.
7. Rattenborg NC, Lesku JA and Libourel P-A. 2022. Sleep in nonmammalian vertebrates. In: Kryger MH (ed.), Principles and Practice of Sleep Medicine, 7th edition. Philadelphia: Elsevier, in press.
*Finally, comparative aspects of sleep have returned to this seventh edition of the ‘Sleep Bible’ following a 28 year hiatus! Here, comparative colleagues and I review sleep (notably) in avian and non-avian reptiles in what is likely to be the most comprehensive coverage to date. My heart-felt appreciation goes out to colleagues, Drs Niels Rattenborg and Paul-Antoine Libourel.
That’s it! Stay tuned for more announcements in the coming weeks. And in the meantime and going forward, whenever you feel work is bogged down with empty electronic mail, plodding paperwork, and mindless meetings, remember the unending, original, creative, important, and inspiring work you conduct on a daily basis. Focus on that and everything else seems mightily unimportant. Because each of you, here, had the unique and enthralling privilege to learn something – to discover something – first. Before anyone else on the planet. Who cool is that? What a high.
Congratulations to you all on Your Series of Successes. As always, I’m eternally proud.
Sleep Ecophysiology Group 