Obstructive sleep apnea and cognitive functioning in the older general population: The moderating effect of age, sex, ApoE4, and obesity.

Research on the relationship between obstructive sleep apnea and cognitive functioning has yielded conflicting results, particularly in the older population, and moderators of this association have rarely been studied. Here we investigated the cross-sectional association between obstructive sleep apnea and cognitive functioning as well as the moderating effect of age, sex, apolipoprotein E4, and obesity on this association among community-dwelling older people. We analysed data from 496 participants (71.4 ± 4.4 years; 45.6% men) of the HypnoLaus study who underwent polysomnography and a battery of neuropsychological tests. The sample was categorised as no-to-mild obstructive sleep apnea (apnea-hypopnea index 0-14.9/h; reference), moderate obstructive sleep apnea (apnea-hypopnea index 15.0-29.9/h), or severe obstructive sleep apnea (apnea-hypopnea index ≥30/h). Regression and moderation analyses were performed with adjustment for confounders. Apolipoprotein E4 and obesity moderated the association between severe obstructive sleep apnea and processing speed, whereas no moderating effects were found for age and sex. In apolipoprotein E4 carriers only, severe obstructive sleep apnea was associated with lower performance in Stroop condition 1 (B = 3.13, p = 0.024). In obese participants only, severe obstructive sleep apnea was associated with lower performance in Stroop condition 1 (B = 3.02, p = 0.025) and Stroop condition 2 (B = 3.30, p = 0.034). Severe obstructive sleep apnea was also associated with lower executive function in the whole sample according to Stroop condition 3 (B = 3.44, p = 0.020) and Stroop interference score (B = 0.24, p = 0.006). Our findings support associations of severe obstructive sleep apnea (but not moderate obstructive sleep apnea) with lower performance in processing speed and executive function in the older general population. Apolipoprotein E4 and obesity appear to be vulnerability factors that strengthen the association between severe obstructive sleep apnea and lower performance in processing speed.

Periodic leg movements during sleep and cognitive functioning in the older general population.

OBJECTIVE: The current evidence of a relationship between periodic leg movements during sleep (PLMS) and cognitive functioning is limited and inconsistent. This cross-sectional study assessed associations between PLMS and cognitive functioning among community-dwelling older adults. METHODS: We included community-dwelling older adults who underwent a polysomnography and a cognitive assessment. The PLMS index (PLMI) and PLMS arousal index (PLMAI) were categorized into tertiles: PLMI <5/h (reference), 5-29.9/h, ≥30/h; and PLMAI <1/h (reference), 1-4.9/h, ≥5/h. The cognitive assessment consisted of ten scores covering the main cognitive domains: global cognition, processing speed, executive function, language, episodic verbal memory, and visuospatial function. Associations between PLMI, PLMAI, and cognitive scores were assessed using regression unadjusted and adjusted models. RESULTS: A total of 579 individuals without dementia were included (mean age: 71.5 ± 4.4 years; men 45.4%). The number of participants in the high-PLMI categories, 5-29.9/h and ≥30/h, was 185 (32.0%) and 171 (29.5%), respectively. Participants in the high-PLMI categories showed no significant difference compared to the reference group regarding their cognitive performance according to the unadjusted and adjusted models. Similarly, we found no association between PLMAI severity and cognitive functioning. CONCLUSIONS: This study shows no cross-sectional association between PLMS severity and cognitive functioning among community-dwelling older adults. However, given the paucity of data in this field, further studies are needed to clarify the relationship between PLMS and cognitive functioning.

Objective polysomnography-based sleep features and major depressive disorder subtypes in the general population.

Insomnia and its opposite hypersomnia are part of the diagnostic criteria for major depressive disorder (MDD). However, no study has investigated whether the postulated sleep alterations in clinical subtypes of MDD are reflected in polysomnography (PSG)-derived objective sleep measures. The objective of this study was to establish associations between the melancholic, atypical and unspecified subtypes of MDD and objective PSG-based sleep features. This cross-sectional analysis included 1820 community-dwelling individuals who underwent PSG and a semi-structured psychiatric interview to elicit diagnostic criteria for MDD and its subtypes. Adjusted robust linear regression was used to assess associations between MDD subtypes and PSG-derived objective sleep measures. Current melancholic MDD was significantly associated with decreased absolute delta power and sleep efficiency and with increased wake after sleep onset. Remitted unspecified MDD was significantly associated with increased rapid eye movements density. No other significant associations were identified. Our findings reflect that some PSG-based sleep features differed in MDD subtypes compared with no MDD. The largest number of significant differences were observed for current melancholic MDD, whereas only rapid eye movements density could represent a risk factor for MDD as it was the only sleep measure that was also associated with MDD in remitted participants.

Pulse Wave Amplitude Drops Index: A Biomarker of Cardiovascular Risk in Obstructive Sleep Apnea.

Rationale: It is currently unclear which patients with obstructive sleep apnea (OSA) are at increased cardiovascular risk. Objective: To investigate the value of pulse wave amplitude drops (PWADs), reflecting sympathetic activations and vasoreactivity, as a biomarker of cardiovascular risk in OSA. Methods: PWADs were derived from pulse oximetry-based photoplethysmography signals in three prospective cohorts: HypnoLaus (N = 1,941), the Pays-de-la-Loire Sleep Cohort (PLSC; N = 6,367), and "Impact of Sleep Apnea syndrome in the evolution of Acute Coronary syndrome. Effect of intervention with CPAP" (ISAACC) (N = 692). The PWAD index was the number of PWADs (>30%) per hour during sleep. All participants were divided into subgroups according to the presence or absence of OSA (defined as ⩾15 or more events per hour or <15/h, respectively, on the apnea-hypopnea index) and the median PWAD index. Primary outcome was the incidence of composite cardiovascular events. Measurements and Main Results: Using Cox models adjusted for cardiovascular risk factors (hazard ratio; HR [95% confidence interval]), patients with a low PWAD index and OSA had a higher incidence of cardiovascular events compared with the high-PWAD and OSA group and those without OSA in the HypnoLaus cohort (HR, 2.16 [1.07-4.34], P = 0.031; and 2.35 [1.12-4.93], P = 0.024) and in the PLSC (1.36 [1.13-1.63], P = 0.001; and 1.44 [1.06-1.94], P = 0.019), respectively. In the ISAACC cohort, the low-PWAD and OSA untreated group had a higher cardiovascular event recurrence rate than that of the no-OSA group (2.03 [1.08-3.81], P = 0.028). In the PLSC and HypnoLaus cohorts, every increase of 10 events per hour in the continuous PWAD index was negatively associated with incident cardiovascular events exclusively in patients with OSA (HR, 0.85 [0.73-0.99], P = 0.031; and HR, 0.91 [0.86-0.96], P < 0.001, respectively). This association was not significant in the no-OSA group and the ISAACC cohort. Conclusions: In patients with OSA, a low PWAD index reflecting poor autonomic and vascular reactivity was independently associated with a higher cardiovascular risk.

Effect of oxybutynin and reboxetine on obstructive sleep apnea: a randomized, placebo-controlled, double-blind, crossover trial.

STUDY OBJECTIVES: Although recent investigations combining noradrenergic and antimuscarinic drugs have shown promising short-term results to treat obstructive sleep apnea (OSA), the mid-term effect and optimal dosage remain uncertain. The present study aimed to evaluate the effect of 1 week of 5 mg oxybutynin and 6 mg reboxetine (oxy-reb) on OSA versus placebo. METHODS: We performed a randomized, placebo-controlled, double-blind, crossover trial comparing the effect of 1 week of oxy-reb versus 1 week of placebo on OSA severity. At-home polysomnography was performed at baseline and after each week of intervention. RESULTS: Fifteen participants (male 66.7%) aged 59 [44-62] years (median [interquartile range]) with a mean body mass index of 33.1 ± 6.6 kg/m2 were included. No significant difference in apnea-hypopnea index (AHI) was observed between conditions (estimated marginal means [95% confidence interval] at baseline: 39.7 [28.5-55.3]; oxy-reb: 34.5 [22.7-52.3]; placebo: 37.9 [27.1-52.9]; p = 0.652), but oxy-reb improved average oxygen desaturation (p = 0.016) and hypoxic burden (p = 0.011) and lowered sleep efficiency (p = 0.019) and rapid eye movement sleep (p = 0.002). Moreover, participants reported reduced sleep quality during the week of oxy-reb compared to the week of placebo (4.7 [3.5; 5.9] vs. 6.5 [5.5; 7.5] on a 0-10 visual analogic scale, respectively; p = 0.001). No significant differences in sleepiness, vigilance, and fatigue were observed. No serious adverse events occurred. CONCLUSIONS: Administration of oxybutynin 5 mg and reboxetine 6 mg did not improve OSA severity assessed by AHI, but did alter sleep architecture and sleep quality. Reduced average oxygen desaturation and hypoxic burden were also observed. CLINICAL TRIAL: ClinicalTrials.gov, https://clinicaltrials.gov, NCT04394143.

Association Between Sleep Microstructure and Incident Hypertension in a Population-Based Sample: The HypnoLaus Study.

Background Poor sleep quality is associated with increased incident hypertension. However, few studies have investigated the impact of objective sleep structure parameters on hypertension. This study investigated the association between sleep macrostructural and microstructural parameters and incident hypertension in a middle- to older-aged sample. Methods and Results Participants from the HypnoLaus population-based cohort without hypertension at baseline were included. Participants had at-home polysomnography at baseline, allowing assessment of sleep macrostructure (nonrapid eye movement sleep stages 1, 2, and 3; rapid eye movement sleep stages; and total sleep time) and microstructure including power spectral density of electroencephalogram in nonrapid eye movement sleep and spindles characteristics (density, duration, frequency, amplitude) in nonrapid eye movement sleep stage 2. Associations between sleep macrostructure and microstructure parameters at baseline and incident clinical hypertension over a mean follow-up of 5.2 years were assessed with multiple-adjusted logistic regression. A total of 1172 participants (42% men; age 55±10 years) were included. Of these, 198 (17%) developed hypertension. After adjustment for confounders, no sleep macrostructure features were associated with incident hypertension. However, low absolute delta and sigma power were significantly associated with incident hypertension where participants in the lowest quartile of delta and sigma had a 1.69-fold (95% CI, 1.00-2.89) and 1.72-fold (95% CI, 1.05-2.82) increased risk of incident hypertension, respectively, versus those in the highest quartile. Lower spindle density (odds ratio, 0.87; 95% CI, 0.76-0.99) and amplitude (odds ratio, 0.98; 95% CI, 0.95-1.00) were also associated with higher incident hypertension. Conclusions Sleep microstructure is associated with incident hypertension. Slow-wave activity and sleep spindles, 2 hallmarks of objective sleep continuity and quality, were inversely and consistently associated with incident hypertension. This supports the protective role of sleep continuity in the development of hypertension.

The Relationship Between Postoperative Opioid Analgesia and Sleep Apnea Severity in Patients Undergoing Hip Arthroplasty: A Randomized, Controlled, Triple-Blinded Trial.

PURPOSE: Residual postoperative pain after hip arthroplasty is usually treated with oral opioids. While classic opioids are associated with respiratory depression and worsening of sleep apnea, tramadol has been reported to preserve respiratory function. However, this has not been investigated in a prospective trial using respiratory polygraphy. This randomized controlled triple-blinded trial tested the hypothesis that postoperative treatment with oral opioids such as oxycodone would increase sleep apnea severity, measured with a respiratory polygraphy, compared with oral tramadol. PATIENTS AND METHODS: Sixty patients undergoing hip arthroplasty under spinal anesthesia with 15 mg isobaric bupivacaine 0.5% were randomized to receive postoperative pain treatment with either oral oxycodone (controlled-release 10 mg every 12 hours and immediate-release 5 mg every 4 hours as needed) or oral tramadol (controlled-release 100 mg every 8 hours and immediate-release 50 mg every 4 hours as needed). Respiratory polygraphy was performed on the first postoperative night. The primary outcome was the apnea-hypopnea index in the supine position. Secondary outcomes included the oxygen desaturation index, postoperative pain scores and intravenous morphine consumption. RESULTS: Mean supine apnea-hypopnea index on postoperative night 1 was 11.3 events.h-1 (95% confidence interval, 4.8-17.7) in the oxycodone group and 10.7 (4.6-16.8) events.h-1 in the tramadol group (p=0.89). There were no significant differences between the oxycodone and tramadol groups with respect to any secondary sleep-related or pain-related outcomes. CONCLUSION: Oral oxycodone did not increase sleep apnea severity measured using respiratory polygraphy compared with oral tramadol on the first postoperative night after hip arthroplasty. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov - NCT03454217 (date of registration: 05/03/2018).

Impact of night and shift work on metabolic syndrome and its components: a cross-sectional study in an active middle-to-older-aged population-based sample.

OBJECTIVES: To examine the effects of work schedules on metabolic syndrome and its components in active middle-to-older-aged workers. METHODS: A cross-sectional analysis including middle-to-older-aged active workers from the population-based CoLaus|PsyCoLaus study (Lausanne, Switzerland) was performed. Work schedule was self-reported and defined as follows: permanent day, day shift, night shift and permanent night work. Associations between work schedule and the risk of metabolic syndrome and its components were analysed using multivariable-adjusted logistic regressions. RESULTS: A total of 2301 active workers (median age (IQR): 55.4 (50.8 to 60.4), 50.1% women) were included. Of these, 1905 were permanent day workers, 220 were day-shift workers, 134 were night-shift workers and 42 were permanent night-shift workers. There were significant interactions between sex and work schedule for metabolic syndrome, high triglycerides and visceral obesity. Men but not women permanent night workers had a higher prevalence of metabolic syndrome than permanent day workers in multivariable-adjusted analyses (OR 4.45 (95% CI 1.36 to 14.56)). Analysis of metabolic syndrome subcomponents showed that the association between work schedule and metabolic syndrome in men was mainly driven by visceral obesity (OR 3.35 (95% CI 1.04 to 10.76)). Conversely, women but not men working in night shift were at increased risk of having high triglycerides compared with permanent day workers (OR 2.92 (95% CI 1.03 to 8.27)). CONCLUSIONS: The risk of metabolic syndrome is higher in men working in permanent night shift compared with permanent day work, and this association could be mediated by visceral obesity.

Intrathecal morphine and sleep apnoea severity in patients undergoing hip arthroplasty: a randomised, controlled, triple-blinded trial.

BACKGROUND: Intrathecal morphine prolongs analgesia after surgery, but has been implicated in postoperative respiratory depression or apnoeic episodes. However, this has not been investigated in a prospective trial using respiratory polygraphy. This randomised controlled triple-blinded trial tested the hypothesis that intrathecal morphine increases sleep apnoea severity, measured using respiratory polygraphy. METHODS: Sixty subjects undergoing hip arthroplasty under spinal anaesthesia received either 15 mg isobaric bupivacaine 0.5% with 0.5 ml normal saline 0.9% (control group) or 15 mg isobaric bupivacaine 0.5% with 0.5 ml intrathecal morphine 100 µg (intrathecal morphine group). Respiratory polygraphy was performed before surgery and on the first and third postoperative nights. The primary outcome was the apnoea-hypopnoea index in the supine position (supine AHI) on the first postoperative night. Secondary outcomes included supine AHI on the third postoperative night, oxygen desaturation index (ODI), and ventilatory frequency during the first and third postoperative nights. RESULTS: On the first postoperative night, mean (95% confidence interval) values for supine AHI were 20.6 (13.9-27.3) and 21.2 (12.4-30.0) events h-1 in the control and intrathecal morphine groups, respectively (P=0.90). There were no significant between-group differences for any of the secondary outcomes, except for a significantly higher central and mixed apnoea index preoperatively and significantly lower mean SpO2 on the third postoperative night in the control group. CONCLUSIONS: Intrathecal morphine did not increase sleep apnoea severity when measured using respiratory polygraphy. Of note, all patients had an increased number of apnoeic episodes on the third postoperative night. CLINICAL TRIAL REGISTRATION: NCT02566226.

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.

Night work and prostate cancer risk: results from the EPICAP Study.

OBJECTIVE: To investigate the role of night work in prostate cancer based on data from the EPICAP Study. METHODS: EPICAP is a French population-based case-control study including 818 incident prostate cancer cases and 875 frequency-matched controls that have been interviewed face to face on several potential risk factors including lifetime occupational history. Detailed information on work schedules for each job (permanent or rotating night work, duration, total number of nights, length of the shift, number of consecutive nights) as well as sleep duration and chronotype, was gathered. Prostate cancer aggressiveness was assessed by Gleason Score. RESULTS: Night work was not associated with prostate cancer, whatever the aggressiveness of prostate cancer, while we observed an overall increased risk among men with an evening chronotype (OR=1.83, 95% CI 1.05 to 3.19). A long duration of at least 20 years of permanent night work was associated with aggressive prostate cancer (OR=1.76, 95% CI 1.13 to 2.75), even more pronounced in combination with a shift length >10 hours or ≥ 6 consecutive nights (OR=4.64, 95% CI 1.78 to 12.13; OR=2.43, 95% CI 1.32 to 4.47, respectively). CONCLUSION: Overall, ever night work, either permanent or rotating, was not associated to prostate cancer. Nevertheless, our results suggest that a long duration of permanent night work in combination with a long shift length or at least six consecutive nights may be associated with prostate cancer, particularly with aggressive prostate cancer. Further studies are needed to confirm those findings.

Slow-wave sleep: From the cell to the clinic.

In recent decades, increasing evidence has positioned slow-wave sleep (SWS) as a major actor in neurophysiological phenomena such as glucose metabolism, hormone release, immunity and memory. This proposed role for SWS, coupled with observations of impaired SWS in several pathologies as well as in aging, has led some researchers to implement methods that could specifically enhance SWS. This review aims to gather the current knowledge extending from the cell to the clinic, in order to construct an overview of what is currently known about so-called SWS. We slowly expand the view from the molecular processes underlying SWS to the cell unit and assembly to cortical manifestations. We then describe its role in physiology and cognition to finally assess its association with clinical aspects. Finally, we address practical considerations for several techniques that could be used to manipulate SWS, in order to improve our understanding of SWS and possibly help the development of treatments for SWS clinical disorders.

Sex-specific associations of different anthropometric indices with acute and chronic insomnia.

Background: Sleep disorders, including insomnia, are risk factors for weight gain. However, few epidemiological studies have investigated the association of anthropometric markers with insomnia as an outcome. Methods: In this observational, cross-sectional study, we assessed the association of 3 different anthropometric indices with acute and chronic insomnia. We used data from 13 389 French adults (mean age= 51.9 ± 13.1 years; 70.3% women) enrolled in the NutriNet-Santé-Biobank cohort. Body weight, height, waist and hip circumference were measured once during a clinic visit (2011-14). Body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) were the main predictors. Acute (past 8 days) and chronic (≥3 months) insomnia were assessed in 2014 via a self-report questionnaire. We fit multivariable logistic regression models providing odds ratios (OR) and 95% confidence intervals (CI). Results: Overweight (25.0 ≤ BMI < 30.0 kg/m2) and general obesity (BMI ≥ 30.0 kg/m2) appeared to have an inverse association with acute insomnia only among men (overweight: OR= 0.80, 95% CI: 0.70, 0.92; obesity: OR= 0.78, 95% CI: 0.63, 0.98). Obesity assessed by BMI and WHR appeared to be positively associated with chronic insomnia only among women (BMI: OR= 1.23, 95% CI: 1.04, 1.45; WHR: OR= 2.24, 95% CI: 1.07, 4.72). WC did not display any significant associations in either sex. Conclusions: These cross-sectional results revealed sex-specific associations of overweight/obesity with different types of insomnia, and merit confirmation longitudinally with objectively assessed sleep parameters. Nonetheless, the findings reinforce the critical importance of joint health behaviour promotion.

Major Change in Body Weight over 5 Years and Total Sleep Time: Investigation of Effect Modification by Sex and Obesity in a Large e-Cohort.

PURPOSE: We assessed the association of long-term weight change ≥5 kg with total sleep time (TST), investigating effect modification by sex and overweight/obesity. METHOD: In a cross-sectional context, we studied 41,610 adults from the general population-based NutriNet-Santé e-cohort. A sleep questionnaire was self-administered in 2014. It included sleep logs for the estimation of average TST at night, and items for the calculation of major weight change as experienced over the previous 5 years. We fit multivariate polytomous logistic regression models. RESULTS: Overall, women with major weight loss had an increased likelihood of short TST (≤6 h) when compared with women with stable weight (OR = 1.15, 95% CI: 1.05-1.25). Individuals with major weight gain had an increased likelihood of short TST compared with their counterparts with stable weight (men: OR = 1.20, 95% CI: 1.05-1.37; women: OR = 1.24, 95% CI: 1.15-1.33). Men with major weight gain were less likely to report long TST compared with men with stable weight (OR = 0.83, 95% CI: 0.70-0.97). Overweight or obesity did not moderate the associations. CONCLUSIONS: The study advances knowledge in the fields of public health and nutrition by providing some evidence of a sex-specific association of major weight change with both short and long TST. These associations merit future investigation in a longitudinal context with repeated, objective measures of both weight and sleep time, while applying more stringent interaction test criteria and accounting for changes in health behaviors.

Shift Work: A Risk Factor for Central Serous Chorioretinopathy.

PURPOSE: To investigate if shift work or sleep disturbances are risk factors for central serous chorioretinopathy (CSCR). DESIGN: Prospective case-control study. METHODS: Forty patients with active CSCR and 40 controls (age- and sex-matched) were prospectively recruited from the Ophthalmology Department of Hôtel Dieu Hospital, Paris, between November 2013 and December 2014. All patients were asked to complete a questionnaire addressing previously described risk factors and working hours, as well as the Insomnia Severity Index (ISI), a validated instrument for assessing sleep disturbances. RESULTS: The mean age of the CSCR group was 44 ± 9 years, whereas the mean age of the control group was 43 ± 10 years. By use of multivariate analysis, shift work (odds ratio [OR] [95% confidence interval]: 5 [1.2-20.4]; P = .02), steroid use (OR: 5.5 [1.1-26.2]; P = .03), and recent psychological stress (OR: 15.3 [4.1-54.5]; P < .001) were found to be independently associated with CSCR. CONCLUSION: The outcomes of this study suggest that shift work is an independent risk factor of CSCR. Further studies are required to confirm these results and to examine if work reconversion would be beneficial in the treatment of patients with chronic/recurrent CSCR.

The role of sleep in the regulation of body weight.

Sleep participates in the regulation of body weight. The amount of sleep and synchronization of the biological clock are both necessary to achieve the energy balance and the secretion of hormones that contribute to weight regulation. In this review, we first reconsider what normal physiological sleep is and what the normative values of sleep are in the general population. Second, we explain how the biological clock regulates the hormones that may be involved in weight control. Third, we provide some recent data on how sleep may be disturbed by sleep disorders or reduced by sleep debt with consequences on weight. Finally, we explore the relationships between sleep debt and obesity.

Benefits of Sleep Extension on Sustained Attention and Sleep Pressure Before and During Total Sleep Deprivation and Recovery.

OBJECTIVES: To investigate the effects of 6 nights of sleep extension on sustained attention and sleep pressure before and during total sleep deprivation and after a subsequent recovery sleep. DESIGN: Subjects participated in two experimental conditions (randomized cross-over design): extended sleep (EXT, 9.8 ± 0.1 h (mean ± SE) time in bed) and habitual sleep (HAB, 8.2 ± 0.1 h time in bed). In each condition, subjects performed two consecutive phases: (1) 6 nights of either EXT or HAB (2) three days in-laboratory: baseline, total sleep deprivation and after 10 h of recovery sleep. SETTING: Residential sleep extension and sleep performance laboratory (continuous polysomnographic recording). PARTICIPANTS: 14 healthy men (age range: 26-37 years). INTERVENTIONS: EXT vs. HAB sleep durations prior to total sleep deprivation. MEASUREMENTS AND RESULTS: Total sleep time and duration of all sleep stages during the 6 nights were significantly higher in EXT than HAB. EXT improved psychomotor vigilance task performance (PVT, both fewer lapses and faster speed) and reduced sleep pressure as evidenced by longer multiple sleep latencies (MSLT) at baseline compared to HAB. EXT limited PVT lapses and the number of involuntary microsleeps during total sleep deprivation. Differences in PVT lapses and speed and MSLT at baseline were maintained after one night of recovery sleep. CONCLUSION: Six nights of extended sleep improve sustained attention and reduce sleep pressure. Sleep extension also protects against psychomotor vigilance task lapses and microsleep degradation during total sleep deprivation. These beneficial effects persist after one night of recovery sleep.

The consensus sleep diary: quantitative criteria for primary insomnia diagnosis.

OBJECTIVE: The aim of the study was to put forward quantitative criteria for the Consensus Sleep Diary, to differentiate people with insomnia from normal sleepers. METHODS: In this retrospective study, we analyzed 295 sleep diaries of patients with primary insomnia (43% were male, ages ranging between 17 and 76 years) collected in two clinical centers for insomnia and 536 sleep diaries of normal sleepers (47% were male, ages ranging between 15 and 82 years). We considered the following sleep parameters: time in bed, sleep onset latency, total sleep time, wake after sleep onset, sleep efficiency, number of awakenings, terminal wakefulness, and subjective feeling of rest. Using the Youden index, we calculated the quantitative criteria that performed best for each sleep parameter. Finally, we created receiver operating characteristic curves to test the accuracy of each identified criterion. RESULTS: Individuals with insomnia significantly differed from controls on all sleep indices (p < .001). Differentiation between individuals with insomnia from controls was optimal for terminal wakefulness (>15 minutes, area under the curve [AUC] = 0.83), wake after sleep onset (cutoff >20 minutes, AUC = 0.81), total sleep time (<390 minutes, AUC = 0.80), and particularly sleep efficiency (<87.5%, AUC = 0.92, sensitivity = 0.80, specificity = 0.90). Time in bed was the least differentiating variable (<500 minutes, AUC = 0.57). CONCLUSIONS: The quantitative criteria of the sleep diary in this study agree with the few available data in the literature. This confirms that the sleep diary could be a useful screening tool for assessing patients with primary insomnia.

Napping reverses increased pain sensitivity due to sleep restriction.

STUDY OBJECTIVE: To investigate pain sensitivity after sleep restriction and the restorative effect of napping. DESIGN: A strictly controlled randomized crossover study with continuous polysomnography monitoring was performed. SETTING: Laboratory-based study. PARTICIPANTS: 11 healthy male volunteers. INTERVENTIONS: Volunteers attended two three-day sessions: "sleep restriction" alone and "sleep restriction and nap". Each session involved a baseline night of normal sleep, a night of sleep deprivation and a night of free recovery sleep. Participants were allowed to sleep only from 02:00 to 04:00 during the sleep deprivation night. During the "sleep restriction and nap" session, volunteers took two 30-minute naps, one in the morning and one in the afternoon. MEASUREMENTS AND RESULTS: Quantitative sensory testing was performed with heat, cold and pressure, at 10:00 and 16:00, on three areas: the supraspinatus, lower back and thigh. After sleep restriction, quantitative sensory testing revealed differential changes in pain stimuli thresholds, but not in thermal threshold detection: lower back heat pain threshold decreased, pressure pain threshold increased in the supraspinatus area and no change was observed for the thigh. Napping restored responses to heat pain stimuli in the lower back and to pressure stimuli in the supraspinatus area. CONCLUSIONS: Sleep restriction induces different types of hypersensitivity to pain stimuli in different body areas, consistent with multilevel mechanisms, these changes being reversed by napping. The napping restorative effect on pain thresholds result principally from effects on pain mechanisms, since it was independent of vigilance status.