Napping reverses increased pain sensitivity due to sleep restriction

Enhanced physical performance, attention, and mood states after a nap opportunity following a sleep restriction night in female athletes: A randomized controlled trial

This study examined the effects of two nap durations (40 minutes (N40) and 90 minutes (N90)) on physical performance, sleepiness, attention, mood states (Profile of Mood States, POMS), perceived exertion (RPE), pain perception (PP), recovery (PRS), and delayed onset muscle soreness (DOMS) in well-trained women. Fourteen female boxers underwent the digit cancellation test, POMS, and the 5-meter shuttle run test (5mSRT) under no-nap (N0), N40, and N90 conditions after either normal sleep (NSN) or sleep restriction (SRN). RPE and PP were assessed immediately post-5mSRT, while PRS and DOMS were recorded at 5 min and 24 h post-5mSRT. Total distance (TD) and higher distance (HD) were better in N40 and N90 after NSN compared to SRN (p < 0.05). Fatigue index (FI) was lower in N40 and N90 than in N0, and lower in N90 than N40 (p < 0.05). PRS improved and RPE, DOMS, and PP decreased significantly after N40 and N90 compared to N0, with N90 showing greater benefits (p < 0.05). Total POMS scores were better after N40 and N90 than N0, with N90 outperforming N40 (p < 0.05). Overall, N90 provided greater benefits than N40 in enhancing physical performance, attention, recovery, and mood, while reducing exertion, pain, and soreness after both NSN and SRN.

The effects, mechanisms and strategies of daytime napping on athletes: a narrative review

Athletes generally suffer from insufficient sleep duration, lower sleep efficiency, and a high overall prevalence of insomnia. Daytime napping has been demonstrated to supplement nighttime sleep in athletes; however, recent controversial findings warrant further consideration. This review synthesized existing studies on the effects of daytime naps on athletes, explored potential mechanisms of daytime napping, and analyzed instances of ineffective interventions or negative outcomes. Daytime napping functions as a restorative strategy to counteract sleep deprivation or the post-lunch dip, assisting athletes in recovering anaerobic capacity, agility, reaction time, and alertness, with potential mechanisms including the reduction of sleepiness through adherence to circadian rhythms, decreased subjective soreness and fatigue attributed to autonomic functioning, and improved respiratory performance. The optimal nap period occurs between 13:00 and 15:00, with a 5-6 h interval between morning awakening and nap initiation. Depending on the athlete's nighttime sleep, opt for a 20 ~ 40 or 60 ~ 90 min nap with at least 60 min between the nap and subsequent exercise to reduce sleep inertia. The intervention efficacy of daytime napping was correlated with exercise intensity. A nap program must be developed based on the specific athletic demands of the sport in practical application.

Comparison of 1-hour floatation-REST versus conventional napping on heart rate variability in active individuals

Objectives

This study aimed to investigate the short-term effects of a 1-hour floatation-resting environmental therapy (FLO) versus conventional napping (NAP) on heart rate variability (HRV) in highly trained individuals.

Methods

20 non-fatigued participants underwent a prospective randomised interventional study comparing the impacts of FLO and NAP on both supine and standing HRV. Measurements were taken before and after each intervention under controlled conditions, and subjective experiences were assessed through questionnaires.

Results

FLO and NAP were associated with changes in HRV parameters but did so differently. NAP significantly enhanced supine parasympathetic activity, as evidenced by increased log-transformed root mean square of successive differences (p=0.02) and power spectral density (p=0.03) relative to heart rate (HR) values, confirming its effectiveness in promoting autonomic recovery. In contrast, despite being better perceived regarding subjective well-being (p=0.04), FLO conferred no significant changes in supine root mean square of successive differences and decreased power spectral density relative to HR (p=0.02). However, post-intervention comparisons were not statistically different. While supine HR decreased significantly following both interventions, standing HR measurements showed a non-significant increase for FLO compared with NAP (p=0.056).

Conclusion

In highly trained individuals, FLO and NAP demonstrated minimal impact on acute autonomic function. NAP appears more effective for enhancing short-term parasympathetic activity, while FLO provides a more enjoyable experience. These findings underscore the importance of personalised recovery strategies and emphasise the need for further research into individual responses and the long-term effects of these interventions.

Sleep Status and Chronotype in University Athletes with and without Chronic Low Back Pain: A Cross-Sectional Study

Objective  This study aimed to evaluate the status of sleep, chronotype, and related variables of university athletes with and without chronic low back pain (CLBP), to find the correlation between CLBP, sleep difficulty score (SDS), and chronotype, and to determine if SDS and chronotype predict CLBP. Methods  Ninety-two university athletes [46 with CLBP (Age: 22.08±2.74 years) and 46 healthy athletes (Age: 22.32±3.11 years) completed the athlete sleep screening questionnaire (ASSQ), also, their demographic, anxiety, depression, and sports-related details were collected. A Pearson correlation and logistic regression models (univariate and multivariate) were used for the statistical analysis. Results  The results demonstrated a higher SDS and evening type preference in CLBP athletes, a significant negative correlation between CLBP and chronotype (r = -0.40, p <0.01), a significant correlation between SDS and CLBP (r = 0.25, p  = 0.01). SDS and chronotype were not found to be significant independent predictors of CLBP. Conclusion  This study concludes that there exists a correlation of CLBP, SDS, and chronotype However, despite the relationship, SDS and chronotype cannot predict CLBP.

Association of night-time sleep and daytime napping with painful temporomandibular disorder

BACKGROUND

Painful temporomandibular disorder (TMD) is the common cause of chronic oro-facial pain, which may interfere with sleep. Previous studies have documented an association between sleep and TMD.

OBJECTIVES

This study aimed to further explore the association of night-time sleep and daytime napping with painful TMD.

METHODS

A total of 419 patients (aged 31.88 ± 11.54 years with women forming 85.4%) from a TMD/Orofacial Pain center were enrolled. Patients' sleep conditions were evaluated with the Pittsburgh Sleep Quality Index (PSQI) questionnaire, and information on night-time sleep duration, napping duration and napping frequency was interviewed. TMD was diagnosed according to the Diagnostic Criteria for TMD protocol and stratified into myalgia (muscle pain), arthralgia (joint pain) and combined (muscle and joint pain) subgroups. The severity of TMD was measured with the Fonseca Anamnestic Index (FAI) questionnaire. Restricted cubic spline (RCS) regression models were established to explore relationships between sleep and painful TMD subgroups.

RESULTS

Patients with poor sleep quality (PSQI≥6) had higher FAI scores (median 60, p < .001) and higher proportions of painful TMDs. The myalgia subgroup had higher PSQI scores (median 8, p < .001) than the arthralgia subgroup. The RCS models indicated a non-linear relationship between night-time sleep duration and myalgia (p < .001), which was not observed in arthralgia. However, there were no significant findings concerning napping and painful TMD subgroups.

CONCLUSION

This study found that the association between sleep and TMD is mainly related to painful TMD conditions, which are associated with night-time sleep duration.

Sleep disorders and orofacial pain: insights for dental practice

In dental sleep medicine several sleep disorders commonly coexist with pain, contributing to complex clinical presentations which might affect the provision of appropriate and timely treatment. There are associations between sleep disorders and pain in general, as well as with specific orofacial pain conditions. As many as five of six patients with orofacial pain can present with sleep problems. The comorbidity of orofacial pain and sleep disorders overlays a complex web of altered neurobiological mechanisms that predispose to the chronification of orofacial pain. This review discusses the relationship between orofacial pain and sleep disorders and highlights their interactions and the neurobiological mechanisms underlying those relationships.

A noradrenergic pathway for the induction of pain by sleep loss

An epidemic of sleep loss currently affects modern societies worldwide and is implicated in numerous physiological disorders, including pain sensitization, although few studies have explored the brain pathways affected by active sleep deprivation (ASD; e.g., due to recreation). Here, we describe a neural circuit responsible for pain sensitization in mice treated with 9-h non-stress ASD. Using a combination of advanced neuroscience methods, we found that ASD stimulates noradrenergic inputs from locus coeruleus (LCNA) to glutamatergic neurons of the hindlimb primary somatosensory cortex (S1HLGlu). Moreover, artificial inhibition of this LCNA→S1HLGlu pathway alleviates ASD-induced pain sensitization in mice, while chemogenetic activation of this pathway recapitulates the pain sensitization observed following ASD. Our study thus implicates activation of the LCNA→S1HLGlu pathway in ASD-induced pain sensitization, expanding our fundamental understanding of the multisystem interplay involved in pain processing.

A Narrative Review of the Reciprocal Relationship Between Sleep Deprivation and Chronic Pain: The Role of Oxidative Stress

Sleep is crucial for human health, insufficient sleep or poor sleep quality may negatively affect sleep function and lead to a state of sleep deprivation. Sleep deprivation can result in various health problems, including chronic pain. The intricate relationship between sleep and pain is complex and intertwined, with daytime pain affecting sleep quality and poor sleep increasing pain intensity. The article first describes the influence of sleep on the onset and development of pain, and then explores the impact of daytime pain intensity on nighttime sleep quality and subsequent pain thresholds. However, the primary emphasis is placed on the pivotal role of oxidative stress in this bidirectional relationship. Although the exact mechanisms underlying sleep and chronic pain are unclear, this review focuses on the role of oxidative stress. Numerous studies on sleep deprivation have demonstrated that it can lead to varying degrees of increased pain sensitivity, while chronic pain leads to sleep deprivation and further exacerbates pain. Further research on the role of oxidative stress in the mechanism of sleep deprivation-induced pain sensitization seems reasonable. This article comprehensively reviews the current research on the interrelationship between sleep deprivation, pain and the crucial role of oxidative stress.

Beneficial Effects of Photoperiod Lengthening on Sleep Characteristics and Mechanical Hyperalgesia in Injured Rats

Sleep and muscle injury-related pain are in negative relationship, and sleep extension may be a favorable countermeasure. In response to muscle injury, an adaptive sleep response has been described in rats, characterized by an increase in total sleep time (TST) and nonrapid eye movement (NREM) sleep. This study examined the effects of photoperiod lengthening (a model of sleep prolongation in rats) on the sleep characteristics of muscle-injured rats and whether this lengthening could benefit injury-induced mechanical hyperalgesia using the Von Frey test. Switching from the conventional 12:12 light/dark (LD) photoperiod (light on: 08:00-20:00) to LD 16:8 (light extended to 24:00) gives rats an extra window of sleep. Our results show higher TST and NREM sleep times in LD 16:8 versus LD 12:12 injured rats during 4 h of light lengthening for 7 d postinjury, showing the efficiency of photoperiod lengthening to increase sleep time in injured rats. In addition, a cumulative effect with the adaptive sleep response to muscle injury occurred with higher TST and NREM sleep times in LD 16:8 injured versus noninjured rats during the dark period, reflecting the high need for sleep after the injury. Greater stability and higher relative delta power of NREM sleep during the extended light period were also observed in injured rats. Finally, the extended photoperiod limits the muscle injury-induced mechanical hyperalgesia for 13 d and allows faster recovery of the baseline mechanical threshold. This is associated with reduced pro-inflammatory cytokines levels in the hippocampus, a brain structure involved in pain processing.

Clinical Phenotypes Supporting the Relationship Between Sleep Disturbance and Impairment of Placebo Effects

Lack of good sleep or insomnia can lead to many health issues, including an elevated risk of cardiovascular disease, obesity, fatigue, low mood, and pain. While chronic pain negatively impacts sleep quality, the relationship between descending pain modulatory systems like placebo effects and sleep quality is not thoroughly known. We addressed this aspect in a cross-sectional study in participants with chronic pain. Placebo effects were elicited in a laboratory setting using thermal heat stimulations delivered with visual cues using classical conditioning and verbal suggestions. We estimated the levels of insomnia severity with the Insomnia Severity Index and the sleep quality with the Pittsburg Sleep Quality Index. The previous night's sleep continuity was assessed as total sleep time, sleep efficiency, and sleep midpoint the night before the experiment. 277 people with chronic pain and 189 pain-free control individuals participated. Participants with chronic pain and insomnia showed smaller placebo effects than those with chronic pain without insomnia. Similarly, poor sleep quality was associated with reduced placebo effects among participants with chronic pain. Clinical anxiety measured by Depression Anxiety Stress Scales partially mediated these effects. In contrast, placebo effects were not influenced by the presence of insomnia or poor sleep quality in pain-free participants. Sleep continuity the night before the experiment did not influence the placebo effects. Our results indicate that participants who experience insomnia and/or poor sleep quality and chronic pain have smaller placebo effects, and that the previous night sleep continuity does not influence the magnitude of placebo effects. PERSPECTIVE: This study examined the relationship between sleep disturbances and experimentally induced placebo effects. We found that individuals with chronic pain who experience insomnia and poor sleep quality demonstrated reduced placebo effects compared to their counterparts with good sleep quality and no insomnia.

The effects of sleep restriction during abstinence on oxycodone seeking: Sex-dependent moderating effects of behavioral and hypothalamic-pituitary-adrenal axis-related phenotypes

During opioid use and abstinence, sleep disturbances are common and are thought to exacerbate drug craving. In this study, we tested the hypothesis that sleep restriction during abstinence from oxycodone self-administration would increase drug seeking during extinction and footshock reinstatement tests. We also performed behavioral phenotyping to determine if individual variation in responses to stressors and/or pain are associated with oxycodone seeking during abstinence, as stress, pain and sleep disturbance are often co-occurring phenomena. Sleep restriction during abstinence did not have selective effects on oxycodone seeking for either sex in extinction and footshock reinstatement tests. Some phenotypes were associated with drug seeking; these associations differed by sex and type of drug seeking assessment. In female rats, pain-related phenotypes were related to high levels of drug seeking during the initial extinction session. In male rats, lower anxiety-like behavior in the open field was associated with greater drug seeking, although this effect was lost when correcting for oxycodone intake. Adrenal sensitivity prior to oxycodone exposure was positively associated with footshock reinstatement in females. This work identifies sex-dependent relationships between HPA axis function and opioid seeking, indicating that HPA axis function could be a therapeutic target for the treatment of opioid use disorder, with tailored approaches based on sex. Sleep disturbance during abstinence did not appear to be a major contributing factor to opioid seeking.

The impact of sleep disturbance on pain perception: A systematic review examining the moderating effect of sex and age

Females have increased pain sensitivity and are more vulnerable to chronic pain conditions. Sleep disturbances are comorbid with chronic pain and exacerbate pain symptoms. Different types of sleep disturbance affect pain perception distinctly, but it is not clear if these effects are equal in men and women. This systematic review investigated potential differences in how sleep disturbance affects pain in males and females. We searched EBSCO, MEDLINE, Psych INFO, Science Direct, and Web of Science from January 2001 to November 2022 and found 38 studies with 978 participants. Separate random-effects models were used to estimate the pooled effect sizes based on standardized mean differences (SMDs) of experimental sleep disturbance paradigms on various pain outcomes. Sex moderated the effect of sleep disturbance on pain facilitation (SMD = 0.13; 95%CI: 0.004 to 0.022; p=.009) and pain inhibition (SMD = 0.033; 95%CI: 0.011 to 0.054; p=.005), with increased facilitation and decreased inhibition in females, but the opposite effect in males. Further, age moderated the effects of total sleep deprivation (SMD = -0.194; 95%CI -0.328 to -0.060; p=.008) on pain sensitivity and fragmented sleep (SMD = -0.110; 95%CI: 0.148 to -0.072; p<.001) on pain threshold. While the moderating effect of sex and age on the sleep-pain relationship was small, these factors need to be considered in future sleep-pain research.

40-min nap opportunity attenuates heart rate and perceived exertion and improves physical specific abilities in elite basketball players

The effect of a 40-min nap opportunity on physiological responses and specific abilities was investigated. Twelve high-level professional basketball players (26.33±5.2 years; 193.17±7.1 m; 87.48±11.2 kg) undertook randomly 40-min nap opportunity (NAP) and control condition (CON). Wellness (Hooper Index) and Epworth Sleepiness Scale (ESS) were measured before and after both conditions. Defensive (DA) and offensive (OA) agility and upper body power (UBP) were assessed after both conditions. Shooting skill (SST) performance was evaluated prior and after a fatiguing task (FT). Heart rate (HR) and rating of perceived exertion (RPE) were recorded during SST-test, FT and SST-retest. ESS, Hooper's stress and fatigue score were significantly lower after nap compared to those before nap (0.009 ≤ p ≤ 0.03). Better performance was obtained in NAP compared to CON condition for DA, OA and UBP (0.0005 ≤ p ≤ 0.02). SST performance was significantly higher in NAP compared to CON in the retest session (p = 0.003, Δ = 20.2%).         The improved performance was associated with significant lower HRpeak (p = 0.01, Δ = 5.25%) and RPE (p = 0.003, Δ = 15.12%). In conclusion, NAP reduced sleepiness and stress and fatigue and enhances physical outcomes of specific skills in elite basketball players.

Dehydrocorydaline alleviates sleep deprivation-induced persistent postoperative pain in adolescent mice through inhibiting microglial P2Y12 receptor expression in the spinal cord

During adolescence, a second period of central nervous system (CNS) plasticity that follows the fetal period, which involves sleep deprivation (SD), becomes apparent. SD during adolescence may result in abnormal development of neural circuits, causing imbalance in neuronal excitation and inhibition, which not only results in pain, but increases the chances of developing emotion disorders in adulthood, such as anxiety and depression. The quantity of surgeries during adolescence is also consistently on the rise, yet the impact and underlying mechanism of preoperative SD on postoperative pain remain unexplored. This study demonstrates that preoperative SD induces upregulation of the P2Y12 receptor, which is exclusively expressed on spinal microglia, and phosphorylation of its downstream signaling pathway p38Mitogen-activated protein/Nuclear transcription factor-κB (p38MAPK/NF-κB)in spinal microglia, thereby promoting microglia activation and microglial transformation into the proinflammatory M1 phenotype, resulting in increased expression of proinflammatory cytokines that exacerbate persisting postoperative incisional pain in adolescent mice. Both intrathecal minocycline (a microglia activation inhibitor) and MRS2395 (a P2Y12 receptor blocker) effectively suppressed microglial activation and proinflammatory cytokine expression. Interestingly, supplementation with dehydrocorydaline (DHC), an extract of Rhizoma Corydalis, inhibited the P2Y12/p38MAPK/NF-κB signaling pathway, microglia activation, and expression of pro-inflammatory cytokines in the model mice. Taken together, the results indicate that the P2Y12 receptor and microglial activation are important factors in persistent postoperative pain caused by preoperative SD in adolescent mice and that DHC has analgesic effects by acting on these targets.

Effect of sleep loss on pain-New conceptual and mechanistic avenues

Introduction

Sleep disturbances increase pain sensitivity in clinical and preclinical settings, but the precise mechanisms are unknown. This represents a major public health issue because of the growing sleep deficiency epidemic fueled by modern lifestyle. To understand the neural pathways at the intersection between sleep and pain processes, it is critical to determine the precise nature of the sleep disruptions that increase pain and the specific component of the pain response that is targeted.

Methods

We performed a review of the literature about sleep disturbances and pain sensitivity in humans and rodents by taking into consideration the targeted sleep stage (REMS, non-NREMS, or both), the amount of sleep lost, and the different types of sleep disruptions (partial or total sleep loss, duration, sleep fragmentation or interruptions), and how these differences might affect distinct components of the pain response.

Results

We find that the effects of sleep disturbances on pain are highly conserved among species. The major driver for pain hypersensitivity appears to be the total amount of sleep lost, while REMS loss by itself does not seem to have a direct effect on pain sensitivity. Sleep loss caused by extended wakefulness preferentially increases pain perception, whereas interrupted and limited sleep strongly dysregulates descending controls such as DNIC, especially in women.

Discussion

We discuss the possible mechanisms involved, including an increase in inflammatory processes, a loss of nociceptive inhibitory pathways, and a defect in the cognitive processing of noxious input.

Sleep deprivation and recovery sleep affect healthy male resident’s pain sensitivity and oxidative stress markers: The medial prefrontal cortex may play a role in sleep deprivation model

Sleep is essential for the body’s repair and recovery, including supplementation with antioxidants to maintain the balance of the body’s redox state. Changes in sleep patterns have been reported to alter this repair function, leading to changes in disease susceptibility or behavior. Here, we recruited healthy male physicians and measured the extent of the effect of overnight sleep deprivation (SD) and recovery sleep (RS) on nociceptive thresholds and systemic (plasma-derived) redox metabolism, namely, the major antioxidants glutathione (GSH), catalase (CAT), malondialdehyde (MDA), and superoxide dismutase (SOD). Twenty subjects underwent morning measurements before and after overnight total SD and RS. We found that one night of SD can lead to increased nociceptive hypersensitivity and the pain scores of the Numerical Rating Scale (NRS) and that one night of RS can reverse this change. Pre- and post-SD biochemical assays showed an increase in MDA levels and CAT activity and a decrease in GSH levels and SOD activity after overnight SD. Biochemical assays before and after RS showed a partial recovery of MDA levels and a basic recovery of CAT activity to baseline levels. An animal study showed that SD can cause a significant decrease in the paw withdrawal threshold and paw withdrawal latency in rats, and after 4 days of unrestricted sleep, pain thresholds can be restored to normal. We performed proteomics in the rat medial prefrontal cortex (mPFC) and showed that 37 proteins were significantly altered after 6 days of SD. Current findings showed that SD causes nociceptive hyperalgesia and oxidative stress, and RS can restore pain thresholds and repair oxidative stress damage in the body. However, one night of RS is not enough for repairing oxidative stress damage in the human body.

Adherence to a Mediterranean Lifestyle and Changes in Frequency, Severity, and Localization of Pain in Older Adults

OBJECTIVE

To assess the association between adherence to a Mediterranean lifestyle and changes in pain, and its characteristics over time in older adults.

PATIENTS AND METHODS

We analyzed data from 864 and 862 community-dwelling individuals aged 65+ years from the Study on Cardiovascular Health, Nutrition and Frailty in Older Adults in Spain (Seniors-ENRICA) Seniors-ENRICA-1 (2008-2010 to 2012) and Seniors-ENRICA-2 (2015-2017 to 2019) cohorts, with a median follow-up of 2.8 and 2.4 years, respectively. Adherence to a Mediterranean lifestyle was assessed at baseline with the 27-item Mediterranean lifestyle (MEDLIFE) index. Pain changes over time were calculated with a pain scale that assessed the frequency, severity, and the number of pain locations both at baseline and follow-up. Multivariable-adjusted relative risk ratios (RRRs) were obtained using multinomial logistic regression.

RESULTS

In the pooled cohorts, after a median follow-up of 2.6 years, pain worsened for 697 participants, improved for 734, and did not change for 295. Compared with the lowest category of MEDLIFE adherence, those in the highest category showed an RRR of improvement vs worsening of overall pain of 1.85 (95% CI, 1.28 to 2.67; P-trend<.001). MEDLIFE adherence was also linked to improvement in pain frequency (RRR, 1.98; 95% CI, 1.31 to 3.01; P-trend=.001), pain severity (RRR, 2.00; 95% CI, 1.33 to 3.00; P-trend=.001), and a reduction in the number of pain locations (RRR, 1.68; 95% CI, 1.13 to 2.50; P-trend=.004). Limitations of this study are the use of self-reported lifestyle data.

CONCLUSION

A Mediterranean lifestyle was associated with improvement of pain characteristics in older adults. Experimental studies should assess the efficacy of an integral lifestyle approach for the management of pain in older adults.

Gut Bless Your Pain—Roles of the Gut Microbiota, Sleep, and Melatonin in Chronic Orofacial Pain and Depression

Background. Increased attention has been paid to the gut–brain axis recently, but little is known so far regarding how this translates into pain susceptibility. Aim. The aim of this review is to determine whether gastroenterological disorders and sleep disorders (directly or indirectly) contribute to an increased susceptibility to depression and chronic orofacial pain. Method. A search was performed in the U.S. National Library of Medicine (PubMed) database in order to find studies published before 19 December 2021. We used the following terms: gut microbiome, OR sleep quality, OR melatonin, OR GERD, OR IBS, AND: depression OR chronic pain, in different configurations. Only papers in English were selected. Given the large number of papers retrieved in the search, their findings were described and organized narratively. Results. A link exists between sleep disorders and gastroenterological disorders, which, by adversely affecting the psyche and increasing inflammation, disturb the metabolism of tryptophan and cause excessive microglial activation, leading to increased susceptibility to pain sensation and depression. Conclusions. Pain therapists should pay close attention to sleep and gastrointestinal disorders in patients with chronic pain and depression.

Relationships of sleep disturbance, intestinal microbiota, and postoperative pain in breast cancer patients: a prospective observational study

PURPOSE

Our study was designed to examine the possible relationship between gut microbiota, sleep disturbances, and acute postoperative pain.

METHODS

Using 16S rRNA sequencing, we analyzed preoperative fecal samples from women undergoing breast cancer surgery. Preoperative sleep disturbance was evaluated with the Pittsburgh Sleep Quality Index (PSQI) questionnaire. Peak and average pain at rest and movement were evaluated 24 h after surgery, using a numerical rating scale (NRS). Preoperative symptoms of depression and anxiety were assessed with the Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7), respectively. Inflammation was measured using white blood cell and neutrophil counts, together with platelet-lymphocyte ratio, and neutrophil-lymphocyte ratio.

RESULTS

Preoperative sleep disturbance was associated with more severe acute postoperative pain. At the phylum level, women with poor sleep quality had higher relative abundance of Firmicutes (p = 0.021) and lower relative abundance of Bacteroidetes (p = 0.013). At the genus level, women with poor sleep quality harbored higher relative abundance of Acidaminococcus and lower relative abundance of several genera. The genus Alloprevotella was negatively associated with peak pain at movement during the first 24 h (r = - 0.592, p < 0.001). The genus Desulfovibrio was negatively associated with symptoms of anxiety (r = - 0.448, p = 0.006). However, partial correlations suggested that the relationship between Alloprevotella and peak pain at movement during the first 24 h was not statistically significant after controlling for sleep (r = - 0.134, p = 0.443).

CONCLUSION

These findings suggest that the changed gut microbiota may be involved in sleep-pain interaction and could be applied as a potential preventive method for postoperative pain.

TRIAL REGISTRATION

The present clinical study has been registered on Chinese Clinical Trial Registry ( www.chictr.org.cn ); the clinical trial registration number is ChiCTR1900021730; the date of registration is March 7, 2019.

Prior Night Sleep Affects Next-Day Pain Interference Among Community-Dwelling Older Adults With Lower Extremity Chronic Pain

Emergent work suggests that sleep is a robust biobehavioral predictor of pain; however, it remains unclear how sleep is prospectively linked to pain on a day-to-day basis among older adults. The current prospective study examined how sleep duration (total sleep time), quality (sleep efficiency, wake after sleep onset), and late and irregular sleep timing influenced next-day pain perception among community-dwelling older adults (N = 10; 65 matched observations) with lower extremity chronic pain over 1 week. Multilevel modeling estimated the association between sleep (Actigraph GT9X Link) and pain perception (Brief Pain Inventory Short Form). Increased wake after sleep onset (B = 0.19, p = 0.04), sleep variability (B = 0.02, p = 0.01), and later midsleep time (B = 0.40, p < 0.05) were associated with increased pain interference the following day. Findings support the idea that timely sleep interventions may reduce the effect of poor sleep on next-day pain in older adults. [Research in Gerontological Nursing, 14(4), 173-179.].

How does sleep help recovery from exercise-induced muscle injuries?

OBJECTIVES

Athletes and military personnel may experience sleep disturbances due to conditions of training and competitions or military missions/field operations. The risk of muscle injuries is greater for them when sleep duration decreases, and training load increases simultaneously, which can be exacerbated by fatigue. Accumulating evidence demonstrates that sleep extension improved performance, pain sensitivity and GH/IGF-I anabolic responses, which may be beneficial in accelerating recovery from muscle injuries.

DESIGN & METHODS

This narrative review describes the importance of sleep for the recovery/prevention of exercise-induced muscle injuries and provides perspectives on the transferability of currently available scientific evidence to the field.

RESULTS

The first part presents the role of sleep and its interaction with the circadian system for the regulation of hormonal and immune responses, and provides information on sleep in athletes and soldiers and its relationship to injury risk. The second part is an overview of muscle injuries in sport and presents the different phases of muscle regeneration and repair, i.e. degeneration, inflammation, regeneration, remodeling and maturation. Part three provides information on the deleterious effects of sleep deprivation on muscle tissue and biological responses, and on the benefits of sleep interventions. Sleep extension could potentially help and/or prevent recovery from exercise-induced muscle-injuries through increasing local IGF-I and controlling local inflammation.

CONCLUSIONS

Although the science of sleep applied to sport is still an emerging field, the current scientific literature shows many potential physiological pathways between sleep and exercise-related muscle injuries. More direct studies are needed to establish clear guidelines for medical personnel and coaches.

Total Sleep Deprivation and Recovery Sleep Affect the Diurnal Variation of Agility Performance: The Gender Differences

ABSTRACT

Romdhani, M, Hammouda, O, Smari, K, Chaabouni, Y, Mahdouani, K, Driss, T, and Souissi, N. Total sleep deprivation and recovery sleep affect the diurnal variation of agility performance: The gender differences. J Strength Cond Res 35(1): 132-140, 2021-This study aimed to investigate the effects of time-of-day, 24 and 36 hours of total sleep deprivation (TSD), and recovery sleep (RS) on repeated-agility performances. Twenty-two physical education students (11 male and 11 female students) completed 5 repeated modified agility T-test (RMAT) sessions (i.e., 2 after normal sleep night [NSN] [at 07:00 and 17:00 hours], 2 after TSD [at 07:00 hours, i.e., 24-hour TSD and at 17:00 hours, i.e., 36-hour TSD], and 1 after RS at 17:00 hours). The RMAT index decreased from the morning to the afternoon after NSN (p < 0.05, d = 1.05; p < 0.01, d = 0.73) and after TSD (p < 0.001, d = 0.92; d = 1.08), respectively, for total time (TT) and peak time (PT). This finding indicates a diurnal variation in repeated agility, which persisted after TSD. However, the diurnal increase in PT was less marked in the female group after NSN (2.98 vs. 6.24%). Moreover, TT and PT increased, respectively, after 24-hour TSD (p < 0.001; d = 0.84, d = 0.87) and 36-hour TSD (p < 0.001, d = 1.12; p < 0.01, d = 0.65). Female subjects' PT was less affected by 24-hour TSD (1.76 vs. 6.81%) compared with male subjects' PT. After 36-hour TSD, the amount of decrease was not different between groups, which increased the diurnal amplitude of PT only for male subjects. Total sleep deprivation suppressed the diurnal increase of PT and increased the diurnal amplitude of oral temperature only in women. Nevertheless, RS normalized the sleep-loss-induced performance disruption. Conclusively, sleep loss and RS differently affect repeated-agility performance of men and women during the day. Sleep extension postdeprivation could have potent restorative effect on repeated-agility performances, and female subjects could extract greater benefits.

Daytime and Nighttime Sleep Characteristics and Pain Among Adults With Stable Heart Failure

BACKGROUND

Pain and sleep disturbance are common among patients with heart failure (HF) and are associated with symptom burden, disability, and poor quality of life. Little is known about the associations between specific sleep characteristics and pain in people with HF.

OBJECTIVE

The aim of this study was to describe the relationships between nocturnal sleep characteristics, use of sleep medication, and daytime sleep characteristics and pain among people with HF.

METHODS

We conducted a cross-sectional study of stable participants with HF. We administered the SF36 Bodily Pain Scale, Pittsburgh Sleep Quality Index, and Sleep Habits Questionnaire and obtained 3 days of wrist actigraphy and 1 night of home unattended polysomnography. We conducted bivariate analyses and generalized linear models.

RESULTS

The sample included 173 participants (mean [SD] age, 60 [16.1] years; 65.3% [n = 113] male). Insomnia symptoms (P = .0010), sleep duration (P = .0010), poor sleep quality (P = .0153), use of sleep medications (P = .0170), napping (P = .0029), and daytime sleepiness (P = .0094) were associated with increased pain. Patients with the longest sleep duration, who also had insomnia, had more pain (P = .0004), fatigue (P = .0028), daytime sleepiness (P = .0136), and poorer sleep quality (P < .0001) and took more sleep medications (P = .0029) than did those without insomnia.

CONCLUSIONS

Pain is associated with self-reported poor sleep quality, napping, daytime sleepiness, and use of sleep medication. The relationship between pain and sleep characteristics differs based on the presence of insomnia and sleep duration. Studies are needed to evaluate the causal relationships between sleep and pain and test interventions for these cooccurring symptoms.

The effects of recovery sleep on pain perception: A systematic review

Experimental studies highlight profound effects of sleep disruptions on pain, showing that sleep deprivation (SD) leads to hyperalgesic pain changes. On the other hand, given that sleep helps normalizing bodily functions, a crucial role of restorative sleep in the overnight restoration of the pain system seems likely. Thus, a systematic review of experimental studies on effects of recovery sleep (RS; subsequently to SD) on pain was performed with the aim to check whether RS resets hyperalgesic pain changes occurring due to SD. Empirical animal and human studies including SD-paradigms, RS and pain assessments were searched in three databases (PubMed, Web of Science, PsycINFO) using a predefined algorithm. 29 studies were included in this review. Most results indicated a reset of enhanced pain sensitivity and vulnerability following RS, especially when total SD was implemented and pressure pain or painful symptoms (human studies) were assessed. Further research should focus on whether and how recovery is altered in chronic pain patients, as this yields implications for pain treatment by enhancing or stabilizing RS.

Total sleep deprivation increases pain sensitivity, impairs conditioned pain modulation and facilitates temporal summation of pain in healthy participants

Chronic pain patients often suffer from insomnia or impaired sleep which has been associated with increased pain sensitivity, but a limited amount of studies have investigated the effects of total sleep deprivation on central pain mechanisms. Therefore, the aim of this study was to determine the effects of total sleep deprivation on temporal summation, conditioned pain modulation, thermal and pressure pain sensitivity in healthy participants. Twenty-four healthy participants took part in this two-session trial. The measurements were conducted after a night of habitual sleep (baseline) and following 24 hours of total sleep deprivation. Detection thresholds for cold and warmth and pain thresholds for cold and heat were assessed. Cuff induced pressure pain detection and tolerance thresholds, temporal summation and conditioned pain modulation were assessed with user-independent, computer-controlled cuff algometry. Conditioned pain modulation was significantly impaired, temporal summation was significantly facilitated and pain sensitivity to pressure and cold pain were significantly increased at follow-up compared with baseline. In conclusion, this study found that one night of total sleep deprivation impaired descending pain pathways, facilitated spinal excitability and sensitized peripheral pathways to cold and pressure pain. Future studies are encouraged to investigate if sleep therapy might normalize pain sensitivity in sleep-deprived chronic pain patients.

Sleep duration and physical function in people with severe obesity: a prospective cross-sectional study

BACKGROUND

Subjects with severe obesity (BMI > 40 kg/m²) have worse physical function and sleep less than lean people (BMI 18.5-25 kg/m²).

METHODS

In 554 subjects with severe obesity, we compared physical function in those with normal sleep duration (NSD, 6-9 h/night), short sleep duration (SSD, ≤ 6 h/night) and long sleep duration (LSD, ≥ 9 h/night).

RESULTS

The mean (±SD) age and BMI were 43.1 (± 11.1) years and 50.9 ± 8.6 kg/m² respectively. One hundred ninety-six (35.4%) were male. More subjects in the NSD group (n = 256) were able to ascend and descend a step 50 times than in the SSD group (n = 247) or the LSD group (n = 51, 75.5% vs 62.8% vs 56.9%, p = 0.002). A similar observation was made for step speed (0.45 ± 0.11 vs 0.43 ± 0.10 vs 0.40 ± 0.11 steps/s respectively, p = 0.001). NSD participants were less likely to have fallen in the preceding year compared to LSD participants (21.1% vs 39.2%, p = 0.007) and also reported less low back pain compared to SSD participants (60.8% vs 75.9%, p = 0.004).

CONCLUSIONS

In conclusion, abnormal sleep duration is associated with reduced physical function in non-elderly severely obese subjects. The effects of sleep hygiene interventions in this cohort warrant further assessment and may be beneficial to their physical function.

Pain complaints are associated with quick returns and insomnia among Norwegian nurses, but do not differ between shift workers and day only workers

PURPOSE

To determine whether common work schedule characteristics among Norwegian nurses were associated with subjective pain complaints.

METHODS

A cross-sectional study in a sample of 1585 nurses, part of the longitudinal questionnaire-based cohort project 'Survey of Shift work, Sleep and Health' (SUSSH). Pain from six regions were assessed: 'headache', 'neck/shoulder/upper back', 'upper extremities', 'lower back', 'lower extremities', and 'abdomen'. Logistic and negative binomial regression (adjusted for age, sex, percentage of full-time equivalent, marital status and children living at home) were conducted where work schedule, number of night shifts last year, number of quick returns (QR) last year (< 11 h between shifts) and insomnia were predictors of localized pain, widespread pain and number of pain sites.

RESULTS

Localized pain, widespread pain and number of pain sites were associated with insomnia (OR 2.06, 95% CI 1.66-2.55, OR 2.14, 95% CI 1.47-3.09, IRR 1.70, 95% CI 1.51-1.91, respectively). Work schedule and number of night shifts worked last year were not associated with any of the three pain measures. Number of QRs worked last year tended to be associated with number of pain sites.

CONCLUSION

The study did not support the hypothesis that non-daytime work schedules are associated with pain complaints. Neither was there support for the hypothesis linking number of night shifts, or the number of QRs, to pain complaints. Future studies should aim to determine the association between QRs and pain in more detail. Pain complaints were associated with insomnia.

[Sleep disorders in chronic pain syndromes]

Sleep disorders and pain syndromes are widespread in the general population. This review presents data on comorbidity of these phenomena and possibility of their mutual influence on each other including data based on long-term prospective studies. Studies of pain syndromes and sleep disorders dynamics are analyzed in detail. Anatomical basis of sleep-pain interactions is described, and results of the emotional influence on sleep and pain associations are presented. Non-pharmacological and drug-based approaches to treatment with detailed description of the biochemical basis of their action are considered. The authors conclude that pain syndromes and sleep disorders have reciprocal relations; the improvement of sleep quality helps in various pain syndromes; sleep normalization could play a preventive role with regard to pain.

Impact of Built Design on Nighttime Family Presence in the Intensive Care Unit

Objective:

Determine whether dedicated family space changes family presence at night in the intensive care unit (ICU).

Purpose:

To measure family presence at night before and after moving to an ICU with in-room family space.

Background:

The safeguarding phenomenon families experience may lead to the desire to sit vigil at the bedside. Lack of dedicated family sleep space may exacerbate sleep deprivation for those who wish to be present at night. Sleep deprivation decreases cognition and capacity for decision-making. Traditionally, ICU rooms have not included dedicated family areas or sleep surfaces. National recommendations include designing new hospital ICU rooms with dedicated family space. It is not known if the built design changes family presence at night.

Method:

Family presence was measured for 30 nights pre- and postmove to a newly built ICU with dedicated family space. The policy for open flexible family presence remained the same before and after the move.

Results:

There was a statistically significant increase in proportion of occupied patient rooms with visitors following the move to the new ICU designed with family space (31% difference, x2= 5.675, 95% CI [5.74, 51.29], p = .0172).

Conclusions:

Families utilize the space when available. Further research is needed to quantify quality and quantity of family sleep and impact on decision-making and interactions with the care team. Sleep deprivation may decrease for families who would have remained in the unit without available family space and sleep surface.

The association between physical and mental chronic conditions and napping

The objectives of this study were to assess the associations among various physical and mental chronic conditions and napping. A cross-sectional epidemiological survey was proposed within the NutriNet-Santé population-based e-cohort launched in France in 2009. Participants were 43,060 French volunteers aged 18 y and over with Internet access. A self-report questionnaire assessing sleep characteristics was administered in 2014. The main outcome (dependent) variable was weekday or weekend napping (yes/no). The main exposure (independent) variables were overweight/obesity, hypertension, diabetes, anxiety and depressive disorders, incident major cardiovascular diseases (myocardial infarction, stroke, unstable angina), and incident cancer (breast and prostate). The associations of interest were investigated with multivariable logistic regression analysis. No significant associations were found between major cardiovascular diseases or breast or prostate cancer and napping. Instead, we found that napping was more common among males (46.1%) than among females 36.9% (p < 0.0001). Individuals who were overweight or obese or had hypertension, diabetes, depression or anxiety disorders had an increased likelihood of napping compared with their healthy peers. The adjusted ORs ranged from 1.14 to 1.28″. In conclusion, most chronic conditions were independently associated with napping. Future longitudinal analyses are needed to elucidate causality.

The Pain of Sleep Loss: A Brain Characterization in Humans

Sleep loss increases the experience of pain. However, the brain mechanisms underlying altered pain processing following sleep deprivation are unknown. Moreover, it remains unclear whether ecologically modest night-to-night changes in sleep, within an individual, confer consequential day-to-day changes in experienced pain. Here, we demonstrate that acute sleep deprivation amplifies pain reactivity within human (male and female) primary somatosensory cortex yet blunts pain reactivity in higher-order valuation and decision-making regions of the striatum and insula cortex. Consistent with this altered neural signature, we further show that sleep deprivation expands the temperature range for classifying a stimulus as painful, specifically through a lowering of pain thresholds. Moreover, the degree of amplified reactivity within somatosensory cortex following sleep deprivation significantly predicts this expansion of experienced pain across individuals. Finally, outside of the laboratory setting, we similarly show that even modest nightly changes in sleep quality (increases and decreases) within an individual determine consequential day-to-day changes in experienced pain (decreases and increases, respectively). Together, these data provide a novel framework underlying the impact of sleep loss on pain and, furthermore, establish that the association between sleep and pain is expressed in a night-to-day, bidirectional relationship within a sample of the general population. More broadly, our findings highlight sleep as a novel therapeutic target for pain management within and outside the clinic, including circumstances where sleep is frequently short yet pain is abundant (e.g., the hospital setting).SIGNIFICANCE STATEMENT Are you experiencing pain? Did you have a bad night of sleep? This study provides underlying brain and behavioral mechanisms explaining this common co-occurrence. We show that sleep deprivation enhances pain responsivity within the primary sensing regions of the brain's cortex yet blunts activity in other regions that modulate pain processing, the striatum and insula. We further establish that even subtle night-to-night changes in sleep in a sample of the general population predict consequential day-to-day changes in pain (bidirectionally). Considering the societal rise in chronic pain conditions in lock-step with the decline in sleep time through the industrial world, our data support the hypothesis that these two trends may not simply be co-occurring but are significantly interrelated.

Sleep duration mediates abdominal and lower-extremity pain after night work in nurses

OBJECTIVES

The aim of this study was to investigate the association between different working shifts (i.e. morning, evening, night shifts) and headache, musculoskeletal and abdominal pain, and the extent to which reduced sleep duration could account for these associations.

METHODS

Nurses (N = 679, 649 female, aged 22-53 years) were followed up for a period of 28 consecutive days, responding to a diary about sleep, shift type and pain complaints (measured on a Likert-type scale ranging from 0 to 3). Generalised structural equation modelling mediation analysis (GSEM) was performed to test whether shift type was associated with higher incidence or higher intensity of pain (headache, pain in neck/shoulders/upper back, upper extremity, low back, lower extremity and abdominal pain), and if this effect was mediated by sleep duration (continuous variable), after controlling for age, work and lifestyle factors.

RESULTS

Pain scores in lower extremities were decreased following night shifts in general. However, when night shifts were followed by short sleep duration, the risk of pain in the lower extremities and abdominal pain were increased. Headache and pain in the upper extremity were increased after night shifts, but were not associated with sleep duration. Pain in the neck/shoulder/upper back and lower back was not related to shift work.

CONCLUSIONS

Among nurses in a three-shift rotating schedule, night shifts increased the risk of pain in several regions, but only pain in the lower extremities and abdomen was related to reduced sleep duration.

Decreased alertness due to sleep loss increases pain sensitivity in mice

Extended daytime and nighttime activities are major contributors to the growing sleep deficiency epidemic, as is the high prevalence of sleep disorders like insomnia. The consequences of chronic insufficient sleep for health remain uncertain. Sleep quality and duration predict presence of pain the next day in healthy subjects, suggesting that sleep disturbances alone may worsen pain, and experimental sleep deprivation in humans supports this claim. We demonstrate that sleep loss, but not sleep fragmentation, in healthy mice increases sensitivity to noxious stimuli (referred to as 'pain') without general sensory hyper-responsiveness. Moderate daily repeated sleep loss leads to a progressive accumulation of sleep debt and also to exaggerated pain responses, both of which are rescued after restoration of normal sleep. Caffeine and modafinil, two wake-promoting agents that have no analgesic activity in rested mice, immediately normalize pain sensitivity in sleep-deprived animals, without affecting sleep debt. The reversibility of mild sleep-loss-induced pain by wake-promoting agents reveals an unsuspected role for alertness in setting pain sensitivity. Clinically, insufficient or poor-quality sleep may worsen pain and this enhanced pain may be reduced not by analgesics, whose effectiveness is reduced, but by increasing alertness or providing better sleep.

Sleep Fragmentation Hypersensitizes Healthy Young Women to Deep and Superficial Experimental Pain

The effect of sleep deprivation on pain sensitivity has typically been studied using total and partial sleep deprivation protocols. These protocols do not mimic the fragmented pattern of sleep disruption usually observed in individuals with clinical pain conditions. Therefore, we conducted a controlled experiment to investigate the effect of sleep fragmentation on pain perception (deep pain: forearm muscle ischemia, and superficial pain: graded pin pricks applied to the skin) in 11 healthy young women after 2 consecutive nights of sleep fragmentation, compared with a normal night of sleep. Compared with normal sleep, sleep fragmentation resulted in significantly poorer sleep quality, morning vigilance, and global mood. Pin prick threshold decreased significantly (increased sensitivity), as did habituation to ischemic muscle pain (increased sensitivity), over the course of the 2 nights of sleep fragmentation compared with the night of normal sleep. Sleep fragmentation did not increase the maximum pain intensity reported during muscle ischemia (no increase in gain), and nor did it increase the number of spontaneous pains reported by participants. Our data show that sleep fragmentation in healthy, young, pain-free women increases pain sensitivity in superficial and deep tissues, indicating a role for sleep disruption, through sleep fragmentation, in modulating pain perception.

PERSPECTIVE

Our findings that pain-free, young women develop hyperalgesia to superficial and deep muscle pain after short-term sleep disruption highlight the need for effective sleep management strategies in patients with pain. Findings also suggest the possibility that short-term sleep disruption associated with recurrent acute pain could contribute to increased risk for future chronic pain conditions.

Napping: A public health issue. From epidemiological to laboratory studies

Sleep specialists have proposed measures to counteract the negative short- and long-term consequences of sleep debt, and some have suggested the nap as a potential and powerful "public health tool". Here, we address this countermeasure aspect of napping viewed as an action against sleep deprivation rather than an action associated with poor health. We review the physiological functions that have been associated positively with napping in both public health and clinical settings (sleep-related accidents, work and school, and cardiovascular risk) and in laboratory-based studies with potential public health issues (cognitive performance, stress, immune function and pain sensitivity). We also discuss the circumstances in which napping-depending on several factors, including nap duration, frequency, and age-could be a potential public health tool and a countermeasure for sleep loss in terms of reducing accidents and cardiovascular events and improving sleep-restriction-sensitive working performance. However, the impact of napping and the nature of the sleep stage(s) involved still need to be evaluated, especially from the perspective of coping strategies in populations with chronic sleep debt, such as night and shift workers.

A qualitative study of sleep quality in children and their resident parents when in hospital

OBJECTIVE

Poor sleep quality impairs immune responses and pain tolerance, both key to recovery from acute illness. Hospitalised children and their co-sleeping parents also risk emotional lability and impaired coping skills when sleep-deprived. We aimed to study the experiences of children and parents during hospital admissions.

DESIGN

Semi-structured interviews were conducted with parents within a week of their child's discharge. Questions explored parent and child sleep quality, factors contributing to this, perceived impact on day-time functioning and suggested improvements to ward sleep environment.

SETTING

Southampton Children's Hospital, UK.

PATIENTS

17 co-sleeping parents of 16 children aged 3-12 years completed interviews. Children admitted for surgical procedures and those with established sleep disorders or nocturnal seizures were excluded.

MAIN OUTCOME MEASURES

Constant comparative methods identified themes within the data using a grounded theory approach.

RESULTS

Parents reported that they, and to a lesser extent their children, experienced reduced sleep quality. Noise and light as well as ward schedules were identified as key factors disrupting sleep. Parents reported that lack of sleep caused difficulties with their own emotional regulation and that of their child, affecting daytime parent-child relationships. Furthermore, they reported a negative impact of sleep deprivation on decision-making about their child's medical care.

CONCLUSIONS

Parents identified poor sleep in hospital as a significant additional burden to their child's hospital admission. Importantly, they identified potential improvements to the ward sleep environment. Intervention studies that target modifiable, child-centred alterations to night-time ward culture are recommended, focusing on measurable child and parental outcomes.

Subjective Sleep Quality Deteriorates Before Development of Painful Temporomandibular Disorder

There is good evidence that poor sleep quality increases risk of painful temporomandibular disorder (TMD). However, little is known about the course of sleep quality in the months preceding TMD onset, and whether the relationship is mediated by heightened sensitivity to pain. The Pittsburgh Sleep Quality Index was administered at enrollment into the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study. Thereafter the Sleep Quality Numeric Rating Scale was administered every 3 months to 2,453 participants. Sensitivity to experimental pressure pain and pinprick pain stimuli was measured at baseline and repeated during follow-up of incident TMD cases (n = 220) and matched TMD-free controls (n = 193). Subjective sleep quality deteriorated progressively, but only in those who subsequently developed TMD. A Cox proportional hazards model showed that risk of TMD was greater among participants whose sleep quality worsened during follow-up (adjusted hazard ratio = 1.73, 95% confidence limits = 1.29, 2.32). This association was independent of baseline measures of sleep quality, psychological stress, somatic awareness, comorbid conditions, nonpain facial symptoms, and demographic characteristics. Poor baseline sleep quality was not significantly associated with baseline pain sensitivity or with subsequent change in pain sensitivity. Furthermore the relationship between sleep quality and TMD incidence was not mediated via baseline pain sensitivity or change in pain sensitivity.

PERSPECTIVE

Subjective sleep quality deteriorates progressively before the onset of painful TMD, but sensitivity to experimental pain does not mediate this relationship. Furthermore, the relationship is independent of potential confounders such as psychological stress, somatic awareness, comorbid conditions, nonpain facial symptoms, and various demographic factors.

The effect of sleep deprivation on pain perception in healthy subjects: a meta-analysis

BACKGROUND

There is strong evidence indicating an interaction between sleep and pain. However, the size of this effect, as well as the clinical relevance, is unclear. Therefore, this meta-analysis was conducted to quantify the effect of sleep deprivation on pain perception.

METHODS

A systematic literature search was conducted using the electronic databases PubMed, Cochrane, Psyndex, Psycinfo, and Scopus. By conducting a random-effect model, the pooled standardized mean differences (SMDs) of sleep deprivation on pain perception was calculated. Studies that investigated any kind of sleep deprivation in conjunction with a pain measurement were included. In cases of several pain measurements within a study, the average effect size of all measures was calculated.

RESULTS

Five eligible studies (N = 190) for the between-group analysis and ten studies (N = 266) for the within-group analysis were identified. Sleep deprivation showed a medium effect in the between-group analysis (SMD = 0.62; CI95: 0.12, 1.12; z = 2.43; p = 0.015) and a large effect in the within-group analysis (SMD = 1.49; CI95: 0.82, 2.17; z = 4.35; p <0.0001). The test for heterogeneity was not significant in the between-group analysis (Q = 5.29; df = 4; p = 0.2584), but it was significant in the within-group analysis (Q = 53.49; df = 9; p <0.0001).

CONCLUSION

This meta-analysis confirms a medium effect (SMD = 0.62) of sleep deprivation on pain perception. As this meta-analysis is based on experimental studies in healthy subjects, the clinical relevance should be clarified.