Reactogenic sleepiness after COVID-19 vaccination. A hypothesis involving orexinergic system linked to inflammatory signals

The Orexin System and Its Impact on the Autonomic Nervous and Cardiometabolic System in Post-Acute Sequelae of COVID-19

Orexins (OXs) are critical for regulating circadian rhythms, arousal, appetite, energy metabolism, and electrolyte balance, affecting both the autonomic nervous system (ANS) and the cardiovascular system (CVS). Disruption of the OX system can result in symptoms similar to those observed in post-acute sequelae of COVID-19 (PASC). This review emphasizes the adverse effects of OX dysregulation on autonomic and cardiometabolic functions in patients with PASC. Additionally, we highlight the potential of anti-OX therapies to provide neuroprotective, anti-inflammatory, and immunoregulatory benefits, offering hope for alleviating some of the debilitating symptoms associated with PASC.

Long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder

OBJECTIVE/BACKGROUND

The short-term efficacy and safety of daridorexant, a dual orexin receptor antagonist, has been demonstrated in Japanese patients with insomnia disorder. The objective of this study was to evaluate, in a non-overlapping patient population to the short-term study, the long-term safety and efficacy of daridorexant in Japanese patients with insomnia disorder.

PATIENTS/METHODS

In this Phase 3 open-label study conducted in Japan, 154 patients with insomnia disorder were randomized to daridorexant 50 mg (n = 102) or 25 mg (n = 52) for 52 weeks. The primary objective was to assess the safety and tolerability of daridorexant for up to 1 year. Secondary exploratory objectives were to evaluate the long-term efficacy of daridorexant on subjective sleep parameters (total sleep time, latency to sleep onset and wake after sleep onset) and daytime functioning (Insomnia Daytime Symptoms and Impacts Questionnaire).

RESULTS

The incidence of treatment-emergent adverse events (TEAEs) was 74 % and 58 % in the 50 mg and 25 mg groups respectively. No serious drug-related TEAEs were reported. Both doses improved next-morning sleepiness (Visual Analog Scale) throughout the study. Five adjudicated adverse events of special interest were reported; excessive daytime sleepiness (n = 1, 25 mg; n = 2, 50 mg), sleep paralysis (n = 1, 50 mg) and nightmare (n = 1, 25 mg). Improvements in sleep and daytime functioning were maintained from Week 2 (first assessment) through to Week 52 in both dose groups.

CONCLUSIONS

Up to 52-weeks, daridorexant was well tolerated with sustained improvement in sleep onset, sleep maintenance and daytime functioning, supporting its long-term use in Japanese patients with insomnia disorder.

β-Lapachone Exerts Hypnotic Effects via Adenosine A1 Receptor in Mice

Sleep is one of the most essential physiological phenomena for maintaining health. Sleep disturbances, such as insomnia, are often accompanied by psychiatric or physical conditions such as impaired attention, anxiety, and stress. Medication used to treat insomnia have concerns about potential side effects with long-term use, so interest in the use of alternative medicine is increasing. In this study, we investigated the hypnotic effects of β-lapachone (β-Lap), a natural naphthoquinone compound, using pentobarbital-induced sleep test, immunohistochemistry, real-time PCR, and western blot in mice. Our results indicated that β-Lap exerts a significant hypnotic effect by showing a decrease in sleep onset latency and an increase in total sleep time in pentobarbital-induced sleep model. The results of c-Fos immunostaining showed that β-Lap decreased neuronal activity in the basal forebrain and lateral hypothalamus, which are wakefulness-promoting brain regions, while increasing in the ventrolateral preoptic nucleus, a sleep-promoting region; all these effects were significantly abolished by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), an adenosine A1 receptor (A1R) antagonist. Western blot analysis showed that β-Lap increased extracellular signalregulated kinase phosphorylation and nuclear factor-kappa B translocation from the cytoplasm to the nucleus; these effects were inhibited by DPCPX. Additionally, β-Lap increased the mRNA levels of A1R. Taken together, these results suggest that β-Lap exerts hypnotic effects, potentially through A1R.

Incidence of narcolepsy symptoms after taking COVID-19 vaccines: a Jordanian cross-sectional study

Purpose

Sleeping disorders were reported in many patients who took vaccines during previous pandemics. We aim to investigate the relationship between coronavirus disease 2019 (COVID-19) vaccines and the incidence of narcolepsy symptoms in the Jordanian population.

Materials and Methods

We used a descriptive, cross-sectional, online self-administered survey conducted between December 2022 and May 2023. The survey targeted males and females above the age of 18 years who took any type of COVID-19 vaccine, had no chronic diseases, and had no sleep disorders prior to taking the vaccine. The survey was distributed via social media platforms.

Results

A total of 873 participants were included in this study, consisting of 44.4% males and 55.6% females, with the majority being in the 18-29 age group. Most participants (79.8%) received two vaccine doses, with the Pfizer vaccine being the most common. Nearly half of the participants reported excessive daytime sleepiness. Sleep paralysis and hypnagogic hallucinations were reported by a notable proportion of participants, but no significant differences were found among the vaccine types. Sleep attacks and fragmented nighttime sleep were associated with the number of vaccine doses received, suggesting a possible influence of the dose count on these symptoms. The presence of excessive daytime sleepiness, sudden loss of muscle tone, sleep paralysis, and hypnagogic hallucinations showed no significant association with the number of doses taken.

Conclusion

We hypothesize a possible link between COVID-19 vaccination and the emergence of narcolepsy symptoms in Jordanian individuals. Additional investigations and continuous monitoring to determine the extent of the risk and uncover potential mechanisms behind this connection should be performed.

Psychiatric adverse events associated with the COVID-19 vaccines approved in the Republic of Korea: a systematic review

This systematic review evaluated psychiatric adverse events (AEs) following vaccination against coronavirus disease 2019 (COVID-19). We included studies that reported or investigated psychiatric AEs in individuals who had received an approved COVID-19 vaccine in the Republic of Korea. Systematic electronic searches of Ovid-Medline, Embase, CENTRAL, and KoreaMed databases were conducted on March 22, 2023. Risk of bias was assessed using the Risk of Bias Assessment Tool for Non-randomized Studies 2.0. The study protocol was registered in the International Prospective Register of Systematic Reviews (CRD42023449422). Of the 301 articles initially selected, 7 were included in the final analysis. All studies reported on sleep disturbances, and 2 highlighted anxiety-related AEs. Sleep disorders like insomnia and narcolepsy were the most prevalent AEs, while depression was not reported. Our review suggests that these AEs may have been influenced by biological mechanisms as well as the broader psychosocial context of the COVID-19 pandemic. Although this study had limitations, such as a primary focus on the BNT162b2 vaccine and an observational study design, it offered a systematic, multi-vaccine analysis that fills a critical gap in the existing literature. This review underscores the need for continued surveillance of psychiatric AEs and guides future research to investigate underlying mechanisms, identify risk factors, and inform clinical management.

Connecting the dots: An updated review of the role of autoimmunity in narcolepsy and emerging immunotherapeutic approaches

BACKGROUND

Narcolepsy type 1 (NT1) is a chronic disorder characterized by pathological daytime sleepiness and cataplexy due to the disappearance of orexin immunoreactive neurons in the hypothalamus. Genetic and environmental factors point towards a potential role for inflammation and autoimmunity in the pathogenesis of the disease. This study aims to comprehensively review the latest evidence on the autoinflammatory mechanisms and immunomodulatory treatments aimed at suspected autoimmune pathways in NT1.

METHODS

Recent relevant literature in the field of narcolepsy, its autoimmune hypothesis, and purposed immunomodulatory treatments were reviewed.

RESULTS

Narcolepsy is strongly linked to specific HLA alleles and T-cell receptor polymorphisms. Furthermore, animal studies and autopsies have found infiltration of T cells in the hypothalamus, supporting T cell-mediated immunity. However, the role of autoantibodies has yet to be definitively established. Increased risk of NT1 after H1N1 infection and vaccination supports the autoimmune hypothesis, and the potential role of coronavirus disease 2019 and vaccination in triggering autoimmune neurodegeneration is a recent finding. Alterations in cytokine levels, gut microbiota, and microglial activation indicate a potential role for inflammation in the disease's development. Reports of using immunotherapies in NT1 patients are limited and inconsistent. Early treatment with IVIg, corticosteroids, plasmapheresis, and monoclonal antibodies has seldomly shown some potential benefits in some studies.

CONCLUSION

The current body of literature supports that narcolepsy is an autoimmune disorder most likely caused by T-cell involvement. However, the potential for immunomodulatory treatments to reverse the autoinflammatory process remains understudied. Further clinical controlled trials may provide valuable insights into this area.

Narcolepsy following COVID-19: A case report and review of potential mechanisms

Key Clinical Message

The immune activation in COVID-19 may trigger narcolepsy in vulnerable patients. We suggest clinicians carefully evaluate patients with post-COVID fatigue and hypersomnia for primary sleep disorders, specifically narcolepsy.

Abstract

The patient is a 33-year-old Iranian woman without a significant past medical history with the full range of narcolepsy symptoms that started within 2 weeks after her recovery from COVID-19. Sleep studies revealed increased sleep latency and three sleep-onset rapid eye movement events, compatible with a narcolepsy-cataplexy diagnosis.

Sleep and Circadian Rhythm in Relation to COVID-19 and COVID-19 Vaccination-National Sleep Survey of South Korea 2022

BACKGROUND

Currently, information on sleep and circadian patterns in relation to COVID-19 or vaccination remains limited. We aimed to investigate sleep and circadian patterns according to history of COVID-19 and COVID-19 vaccination side effects.

METHODS

We used data from the National Sleep Survey of South Korea 2022, a nationwide cross-sectional population-based survey regarding sleep-wake behaviors and sleep problems among Korean adults. Analysis of covariance (ANCOVA) and logistic regression analyses were performed to explore the different sleep and circadian patterns according to the history of COVID-19 or self-reported side effects of the COVID-19 vaccination.

RESULTS

The ANCOVA showed that individuals with a history of COVID-19 presented a later chronotype than individuals without a history of COVID-19. Individuals who had experienced vaccine-related side effects had a shorter sleep duration, poorer sleep efficiency, and worse insomnia severity. Multivariable logistic regression analysis showed a later chronotype related to COVID-19. A short sleep duration, poorer sleep efficiency, and worse insomnia severity were associated with self-reported side effects of the COVID-19 vaccination.

CONCLUSIONS

Individuals who recovered from COVID-19 had a later chronotype than those without a history of COVID-19. Individuals who had experienced vaccine-related side effects presented with poorer sleep than those without side effects.

Side Effects Associated With Homologous and Heterologous COVID-19 Vaccines: A Cross-Sectional Study in Saudi Arabia

BACKGROUND

Numerous studies on coronavirus disease 2019 (COVID-19) vaccination safety have been conducted in Saudi Arabia. Even though there is less evidence comparing the side effects of different vaccines and a few of them studied the side effects of mixing different platforms of vaccines.

OBJECTIVES

This study aimed to evaluate the type and severity of adverse effects following COVID-19 vaccination based on the type and platform of received vaccine and to determine factors that contribute to the occurrence of these side effects.

METHODS

This cross-sectional comparative study was conducted in Saudi Arabia from January to the end of February 2022 among COVID-19 vaccine recipients through an online survey. Based on the type of vaccines received, we categorized our participants into two groups - those who received two doses of either the Pfizer or the AstraZeneca COVID-19 vaccines, and those who received mixed vaccination regimen (one dose of Pfizer and one dose of AstraZeneca).

RESULTS

The study included 1,340 participants, of which 56.3% received two doses of the Pfizer vaccine while (7%) received two doses of the AstraZeneca vaccine, and 8.8% received mixed vaccines (one dose of the Pfizer vaccine and one dose of the AstraZeneca vaccine). Pain at the injection site was the most frequent local symptom (37.9%) followed by swelling±redness (27.6%). The local adverse reactions were nearly equal in AstraZeneca and Pfizer vaccines, whereas these were significantly lower in those who received mixed doses (p<0.001). Fever was significantly higher in mixed vaccination regimens compared to other types (p<0.001). The male gender who received the Pfizer vaccine were at higher risk of developing an adverse reaction following vaccination. Unusual side effects (sleep disorders, menstrual irregularities, and symptoms suggestive of diabetic neuropathy) were also reported.

CONCLUSION

The results suggest the overall safety of Pfizer and AstraZeneca vaccines as well as the mixed vaccination protocol. A heterologous regimen was associated with fewer side effects compared to homologous vaccines. Further studies are needed to assess the long-term side effects.

Adverse events following immunization of COVID-19 vaccine among children aged 6-11 years

Introduction

Starting in December 2021, the Indonesian Government has recommended inactivated SARS-CoV-2 vaccine (CoronaVac) for children aged 6-11 years. This study aims to determine the prevalence and determinant factors of adverse events following immunization (AEFI) of the first dose and the second dose of the COVID-19 vaccine among children aged 6-11 years old.

Materials and methods

We conducted a cross-sectional study in Bantul District, Yogyakarta, Indonesia, in February-March 2022. Data were collected by trained interviews with 1,093 parents of children 6-11 years old who received the first dose and the second dose of the COVID-19 vaccine. Data were analyzed with chi-square and logistic regression.

Results

The prevalence of AEFI in the first dose of the COVID-19 vaccine was 16.7%, while the second dose was 22.6%. The most common symptoms of AEFI at the first dose were local site pain and fever, while at the second dose were cough and cold. Determinants of AEFI of COVID-19 vaccination among children were girls with OR 1.31 (95% CI 1.0-1.7; P 0.04), mass-setting of vaccination with OR 0.70 (95% CI 0.5-0.9; P 0.01), the history of AEFI in childhood vaccination with OR 1.63 (95% CI 1.2-2.2; P < 0.01) and administering other vaccines within 1 month before COVID-19 vaccination, with OR 5.10 (95% CI 2.1-12.3 P < 0.01).

Conclusion

The prevalence of AEFI in the first and the second dose of inactivated COVID-19 vaccine was comparable to that reported in the clinical trial study and the communities. Risk communication should be provided to the child and their parents regarding the risk of mild AEFI of the COVID-19 vaccine, especially for children with a history of AEFI in childhood vaccination and who received other vaccines containing the same adjuvant with CoronaVac within 1 month. A mass-setting of vaccination should be taken as an advantage to educate parents about the risk of AEFI and also about the reporting pathways.