Stimulants and Depressor Drugs in the Sleep-Wake Cycle Modulation: The case of alcohol and cannabinoids

A complex neurobiological network drives the sleep-wake cycle. In addition, external stimuli, including stimulants or depressor drugs, also influence the control of sleep. Here we review the recent advances that contribute to the comprehensive understanding of the actions of stimulants and depressor compounds, such as alcohol and cannabis, in sleep regulation. The objective of this review is to highlight the neurobiological mechanism engaged by alcohol and cannabis in sleep control.

Intrinsic maturation of sleep output neurons regulates sleep ontogeny in Drosophila

The maturation of sleep behavior across a lifespan (sleep ontogeny) is an evolutionarily conserved phenomenon. Mammalian studies have shown that in addition to increased sleep duration, early life sleep exhibits stark differences compared to mature sleep with regard to the amount of time spent in certain sleep states. How intrinsic maturation of sleep output circuits contributes to sleep ontogeny is poorly understood. The fruit fly Drosophila melanogaster exhibits multifaceted changes to sleep from juvenile to mature adulthood. Here, we use a non-invasive probabilistic approach to investigate changes in sleep architecture in juvenile and mature flies. Increased sleep in juvenile flies is driven primarily by a decreased probability of transitioning to wake, and characterized by more time in deeper sleep states. Functional manipulations of sleep-promoting neurons in the dFB suggest these neurons differentially regulate sleep in juvenile and mature flies. Transcriptomic analysis of dFB neurons at different ages and a subsequent RNAi screen implicate genes involved in distinct molecular processes in sleep control of juvenile and mature flies. These results reveal that dynamic transcriptional states of sleep output neurons contribute to changes in sleep across the lifespan.

α-Synuclein Responses in the Laterodorsal Tegmentum, the Pedunculopontine Tegmentum, and the Substantia Nigra: Implications for Early Appearance of Sleep Disorders in Parkinson’s Disease

Background: Parkinson’s disease (PD) is a neurodegenerative disorder associated with insoluble pathological aggregates of the protein α-synuclein. While PD is diagnosed by motor symptoms putatively due to aggregated α-synuclein-mediated damage to substantia nigra (SN) neurons, up to a decade before motor symptom appearance, patients exhibit sleep disorders (SDs). Therefore, we hypothesized that α-synuclein, which can be present in monomeric, fibril, and other forms, has deleterious cellular actions on sleep-control nuclei. Objective: We investigated whether native monomer and fibril forms of α-synuclein have effects on neuronal function, calcium dynamics, and cell-death-induction in two sleep-controlling nuclei: the laterodorsal tegmentum (LDT), and the pedunculopontine tegmentum (PPT), as well as the motor-controlling SN. Methods: Size exclusion chromatography, Thioflavin T emission, and circular dichroism spectroscopy were used to isolate structurally defined forms of recombinant, human α-synuclein. Neuronal and viability effects of characterized monomeric and fibril forms of α-synuclein were determined on LDT, PPT, and SN neurons using electrophysiology, calcium imaging, and neurotoxicity assays. Results: In LDT and PPT, both forms of α-synuclein induced excitation and increased calcium, and the monomeric form heightened putatively excitotoxic neuronal death, whereas, in the SN we saw inhibition, decreased intracellular calcium, and monomeric α-synuclein was not associated with heightened cell death. Conclusion: Nucleus-specific differential effects suggest mechanistic underpinnings of SDs’ prodromal appearance in PD. While speculative, we hypothesize that the monomeric form of α-synuclein compromises functionality of sleep-control neurons, leading to the presence of SDs decades prior to motor dysfunction.

Does Reading a Book in Bed Make a Difference to Sleep in Comparison to Not Reading a Book in Bed? The People's Trial- an Online, Pragmatic, Randomised Trial

BackgroundThe best way of comparing healthcare treatments is through a randomised trial. In a randomised trial, we compare something (a treatment or intervention) to something else, often another treatment. Who gets what is decided at random, meaning everyone has an equal chance of getting any of the treatments. This means any differences found can be put down to the treatment received rather than other things, such as where people live, or health conditions they might have.The People’s Trial aimed to help the public better understand randomised trials by inviting them to design and carry out a trial. The question chosen by the public for The People’s Trial was:‘Does reading a book in bed make a difference to sleep, in comparison to not reading a book in bed?’ This paper describes that trial, called ‘The Reading Trial’.MethodsThe Reading Trial was an online, randomised trial. Members of the public were invited to take part through social media campaigns. People were asked to either read a book in bed before going to sleep (intervention group) or not read a book in bed before going to sleep (control group). We asked everyone to do this for seven days, after which they measured their sleep quality. Results During December 2019, a total of 991 people took part in The Reading Trial, half (496 (50%)) in the intervention group and half (495 (50%)) in the control group. Not everyone finished the trial: 127 (25.6%) people in the intervention group, and 90 (18.18%) people in the control group. Of those providing data, 156/369 (42%) people in the intervention group felt their sleep improved, compared to 112/405 (28%) of those in the control group, a difference of 14%. When we consider how certain we are of this finding, we estimate that, in The Reading Trial, sleep improved for between 8% and 22% more people in the intervention group compared to the control group.ConclusionsReading a book in bed before going to sleep improved sleep quality, compared to not reading a book in bed.Trial Registration Registered 4th December 2019, ClinicalTrials.gov ID: NCT04185818.

776 Perceived sleep control and nightmares distinguish college students with suicidal ideation from past attempters

Introduction Suicidal ideation is common in college-aged students, but this is limited as a risk factor because ideation rarely leads to suicide attempts. Disrupted sleep increases suicide risk, but it is unclear whether this relationship applies equally to both ideators and attempters. Therefore, the present study explored four different sleep variables as discriminators between past suicidal ideation and a past suicide attempt. Methods Data from N=506 respondents were collected as part of the Assessing Nocturnal Sleep/Wake Effects on Risk of Suicide (ANSWERS) Survey in college students. The primary outcomes, lifetime history of suicidal ideation or a suicide attempt, were assessed using self-report questions derived from the Columbia Suicide Severity Rating Scale. Predictors were weekday short sleep (≤ 6h; from a retrospective sleep diary), Insomnia Severity Index (ISI) score, Brief Inventory of Sleep Control (BRISC) score, and Disturbing Dreams and Nightmares Severity Index (DDNSI) score. Binomial logistic regression models tested whether these predictors distinguished ideators from attempters. Models were unadjusted, adjusted for age, sex, race, and ethnicity, and additionally adjusted for thwarted belongingness or perceived burdensomeness from the Interpersonal Theory of Suicide. Results A total of N=182 (36%) respondents endorsed lifetime suicidal ideation, while N=61 (12%) reported a prior suicide attempt. Attempters tended to be slightly older (p=0.016), in worse health (p<0.001), and have more severe depression (p<0.001) and anxiety (p<0.001) than ideators. In unadjusted models, higher BRISC scores were associated with reduced odds of a suicide attempt (OR: 0.62 [0.42, 0.90]) while DDNSI scores of >=10 were associated with greater odds of a suicide attempt (OR: 4.24 [1.28, 4.24]). Adjusting for age, sex, race, ethnicity, thwarted belongingness, and perceived burdensomeness attenuated but did not eliminate these relationships. Short sleep and ISI scores did not distinguish ideators from attempters. Conclusion Perceived sleep control and severity of nightmares, but not insomnia or short sleep, distinguished individuals with a history of suicidal ideation from those with a history of a suicide attempt. However, longitudinal research is needed to determine if poor sleep control or nightmares are proximal predictors of a suicide attempt. Support (if any):

775 The Relationship Between Sleep and Suicidal Ideation in College Students

Introduction Suicide is the second-leading cause of death for young adults and insomnia increases suicide risk. However, the data on disrupted sleep and suicidal ideation in college students is mixed, including whether disrupted sleep fits into the framework of the Interpersonal Theory of Suicide. Therefore, the present study explored how four different sleep variables influenced recent suicidal ideation in a collegiate sample. Methods Data from N=506 respondents were collected as part of the Assessing Nocturnal Sleep/Wake Effects on Risk of Suicide (ANSWERS) Survey in college students. The primary outcome, active suicidal ideation in the last 3 months, was assessed using several self-report questions derived from the Columbia Suicide Severity Rating Scale. The predictors were weekday short sleep (≤6h; assessed by retrospective sleep diary), Insomnia Severity Index (ISI) score, Brief Inventory of Sleep Control (BRISC) score, and Disturbing Dreams and Nightmares Severity Index (DDNSI) score. Binomial logistic regression models estimated the associations between suicidal ideation and sleep variables in models that were unadjusted, adjusted for age, sex, race, and ethnicity, and additionally adjusted for thwarted belongingness or perceived burdensomeness (constructs from the Interpersonal Theory of Suicide). Results A total of N=121 (23.9%) respondents endorsed suicidal ideation in the last 3 months. Individuals with suicidal ideation were in poorer health (p<0.001) and had more severe depression (p<0.001) and anxiety (p<0.001). In unadjusted models, individuals were more likely to report suicidal ideation if they had short sleep (OR 1.93 [1.23–3.05]), ISI scores of 8 or more (OR 3.01 [1.94–4.74]), and DDNSI scores of 10 or more (OR 2.66 [1.69–4.19]). Higher BRISC scores were associated with lower odds of suicidal ideation (OR 0.53 [0.41–0.68]). Adjusting for age, sex, race, ethnicity, thwarted belongingness, and perceived burdensomeness attenuated but did not eliminate any of these relationships. Conclusion Insomnia, short sleep, nightmares, and less perceived sleep control were all associated with recent suicidal ideation in college students. Moreover, these findings were generally independent of the Interpersonal Theory of Suicide. Further research is needed to understand how sleep affects suicide risk in this population, and whether sleep interventions can reduce this risk. Support (if any):

210 Changes in Dream Recall During the COVID-19 Pandemic: Associations with Sleep, Stress and Dream Content

Introduction During the COVID-19 pandemic, individuals have faced unprecedented events, which are often stressful. Stress has an important impact on dreams, and stress-induced sleep difficulties may also impact dream recall. The present study evaluated associations between sleep, stress and dream content on dream recall during the pandemic. Methods A sample of N=419 US adults completed online surveys about sleep and COVID-19 experiences. Participants were asked if they remember more, fewer or about the same amount of dreams as before the pandemic. They were also asked whether the pandemic was associated with more stress, a more regular schedule, improved sleep, worse sleep, more early insomnia, more middle-of-the-night insomnia, more sleepiness, and more naps. They also completed the Insomnia Severity Index, Fatigue Severity Scale, Epworth Sleepiness Scale, Brief Index of Sleep Control, Assessment of Sleep Environment, GAD-7 anxiety scale, and PHQ9 depression scale. Multinomial logistic regressions examined correlates of increased or decreased recall (versus same), adjusted for age, sex, and race/ethnicity. Results Those who experienced greater schedule regularity were less likely to report decreased recall (RRR=0.50,p<0.0005), as were those who reported sleep improvement (RRR=0.48,p=0.006). Those whose sleep worsened were more likely to report both increased (RRR=1.64,p=0.003) and decreased (RRR=2.16,p<0.0005) recall. Those suffering maintenance insomnia were more likely to report both increased (RRR=1.70,p=0.001) and decreased (RRR=2.68,p<0.0005) recall, as did those who reported more daytime sleepiness (Increased RRR=1.57,p=0.006; Decreased RRR=1.94,p=0.001). Those whose dream content was more negative were more likely to report both increased (RRR=4.05,p<0.005) and decreased (RRR=3.35,p<0.0005) recall, as did those who reported less negative content (Increased RRR=4.20,p<0.0005; Decreased RRR=5.05,p<0.0005). Similarly, those who reported more positive dream content reported both increased (RRR=17.37,p<0.0005) and decreased (RRR=7.14,p=0.02) recall, as did those who reported less positive content (Increased RRR=4.49,p<0.0005; Decreased RRR=5.59,p<0.0005). Less recall was associated with greater insomnia severity (RRR=1.08,p=0.001), fatigue (RRR=1.04,p=0.001), sleepiness (RRR=1.09,p=0.01), COVID stress (RRR=1.67,p=0.03), anxiety (RRR=1.08,p=0.01), and depression (RRR=1.06,p=0.007), worse sleep environment (RRR=1.06,p=0.005), and less sleep control (RRR=0.56,p=0.001). Conclusion The results of this survey suggest that a sudden decrease in dream recall in reaction to a new stress could be considered as a pejorative indicator regarding sleep quality and mental health. Support (if any) R01MD011600, R01DA051321

029 Median preoptic dual control over sleep regulation

Introduction Previous studies suggest that the median preoptic nucleus (MnPO) plays an important role in regulating the wake-sleep cycle and in particular homeostatic sleep drive. However, the precise cellular phenotypes, targets and central mechanisms by which the MnPO neurons regulate the wake-sleep cycle remain unknown. Both glutamatergic (Vglut2+) and GABAergic (Vgat+) MnPO neurons innervate brain regions implicated in sleep promotion and maintenance, suggesting that both cell types may participate on sleep control. Methods In this study, we used two genetically-targeted approaches associated with electroencephalographic (EEG) and electromyographic (EMG) recordings in Vgat-IRES-cre and Vglut2-IRES-cre mice to investigate the role of the MnPOVgat and MnPOVglut2 neurons in modulating wake-sleep behavior. Results First, using a chemogenetic approach, we found that activation of MnPOVgat neurons reduced the latency for the first NREM sleep episode, produced an increase in NREM sleep and reduced wakefulness. Then, to test the role of MnPOVgat and MnPOVglut2 neurons in regulating sleep homeostasis, we recorded EEG and EMG responses in mice that had the Vgat+ or Vglut2+ neurons deleted from the MnPO. After deletion of MnPOVgat neurons, mice showed a reduction of NREM sleep and an increase in wakefulness during the light phase. Deletion of MnPOVgat neurons also reduced sleep recovery after 4 hours of sleep deprivation (SD). On the other hand, deletion of the MnPOVglut2 neurons did not change the wake-sleep cycle during the 24h baseline condition, but prevented the sleep recovery immediately after SD. To understand the underlying mechanism in preventing sleep recovery in both MnPOVglut2- and MnPOVgat-deleted mice groups, we exposed these animals to a psychological stress protocol. In response to a psychological stressor, mice with deletion of glutamatergic, but not GABAergic MnPO neurons, had an exacerbation of the stress-induced insomnia. Conclusion Our results suggest that both neuron populations differentially participate in wake-sleep control, with MnPOVgat neurons being critically involved in sleep homeostasis, and MnPOVglut2 neurons promoting sleep during allostatic (stressful) challenges. Support (if any) NIH Grants NS085477, NS072337, HL095491 and Sleep Research Society Foundation (Award 026-JP-20).

Astrocytic GABA Transporter controls sleep by modulating GABAergic signaling in Drosophila circadian neurons

A precise balance between sleep and wakefulness is essential to sustain a good quality of life and optimal brain function. GABA is known to play a key and conserved role in sleep control, and GABAergic tone should therefore be tightly controlled in sleep circuits. Here we examined the role of the astrocytic GABA transporter (GAT) in sleep regulation using Drosophila melanogaster. We found that a hypomorphic gat mutation (gat33-1) increased sleep amount, decreased sleep latency, and increased sleep consolidation. Interestingly, sleep defects were suppressed when gat33-1 was combined with a mutation disrupting wide-awake (wake), a gene that regulates the cell-surface levels of the GABAA receptor Resistance to Dieldrin (RDL) in the wake-promoting large ventral lateral neurons (l-LNvs). Moreover, RNAi knockdown of rdl and its modulator dnlg4 in these circadian neurons also suppressed gat33-1 sleep phenotypes. Brain immunohistochemistry showed that GAT-expressing astrocytes were located near RDL-positive l-LNvs cell bodies and dendritic processes. We conclude that astrocytic GAT decreases GABAergic tone and RDL activation in arousal promoting LNvs, thus determining proper sleep amount and quality in Drosophila