A randomized trial of a three-hour protected nap period in a medicine training program: sleep, alertness, and patient outcomes

Association of sleep quality with duty hours, mental health, and medical errors among Japanese postgraduate residents: a cross-sectional study

Long duty hours (DH) impair sleep and negatively affect residents' health and medical safety. This cross-sectional study investigated the association among residents' DH, sleep duration, insomnia, sleep impairment, depressive symptoms, and self-reported medical errors among 5579 residents in Japan who completed the General Medicine In-Training Examination (2021) and participated in the training-environment survey. Weekly DH was classified under seven categories. Sleep duration and insomnia symptoms, from the Athens Insomnia Scale, were analysed to determine sleep impairment; depressive symptoms and medical errors were self-reported. Among 5095 residents, 15.5% slept < 5 h/day, and 26.7% had insomnia. In multivariable analysis, compared with ≥ 60 and < 70, DH ≥ 90 h/week associated with shorter sleep duration and worsen insomnia symptoms. Shorter durations of sleep and more intense symptoms of insomnia were associated with increased depressive symptoms. Medical errors increased only among residents with insomnia, but were not associated with sleep duration. DH > 90 h/week could lead to shorter sleep duration, worsen insomnia symptoms, and negatively impact well-being and medical safety. There was no significant association between sleep duration and medical errors; however, insomnia conferred an increased risk of medical errors. Limiting DH for residents to avoid excessive workload can help improve resident sleep, enhance resident well-being, and potentially reduce insomnia-associated medical errors.

Resident duty hours and resident and patient outcomes: Systematic review and meta-analysis

OBJECTIVES

The policies regarding resident physician work hours are constantly being evaluated and changed. However, the results of randomised control trials (RCTs) are mixed. This systematic review of RCTs aims to synthesise the evidence associated with resident duty hour restrictions and its impact on resident- and patient-based outcomes.

METHODS

A comprehensive search of the Cochrane Library, EMBASE and PubMed was conducted from inception until 31 July 2020. Any RCT evaluating the impact of longer resident physician work hours compared to shorter resident physician work hours on resident- and patient-based outcomes was eligible for inclusion. Two reviewers extracted data independently. The primary outcome was the impact of resident duty hour restrictions on emotional exhaustion, depersonalisation and personal accomplishment, as defined by the Maslach Burnout Inventory. The secondary patient-related outcomes were patient hospital length of stay, serious medical errors and preventable adverse events. Data were pooled using a random-effects model.

RESULTS

Of the 873 references, nine RCTs met the inclusion criteria. A shorter shift length compared with longer shift length was associated with significantly less emotional exhaustion (standardised mean difference [SMD] = -0.11, 95% CI = -0.21, -0.00) and less dissatisfaction with overall well-being (OR = 0.61, 95% CI 0.38, 0.99) but not with hospital length of stay (SMD = -0.01, 95% CI = -0.05, 0.02, p = 0.45) and serious medical errors per 1000 patient hours (OR = 1.07, 95% CI = 0.52, 2.21; p = 0.86).

CONCLUSIONS

Shorter resident duty hours is possibly associated with improvement in resident-based outcomes, specifically, emotional exhaustion, dissatisfaction with overall well-being, sleep duration and sleepiness. These findings may inform the policy change in support of reduced shift hours resulting in overall well-being for the residents with possible reduction in burnout without adverse impact on patient-based outcomes.

Resting and Recharging: A Narrative Review of Strategies to Improve Sleep During Residency Training

BACKGROUND

Residency involves demanding training with long hours that may cause fatigue and sleep deprivation and adversely impact residents and patients under their care.

OBJECTIVE

To identify, using a narrative review, evidence-based interventions to reduce the physiologic effects of fatigue and sleep deprivation from overnight and night shift work.

METHODS

A PubMed literature search was conducted through August 30, 2021, using the terms "resident" and "sleep" in the title or abstract and further narrowed using a third search term. Observational studies, randomized controlled trials, systematic reviews, and meta-analyses of human subjects written and published in English were included. Studies that were not specific to residents or medical interns or did not investigate an intervention were excluded. Additional studies were identified by bibliography review. Due to the heterogeneity of study design and intervention, a narrative review approach was chosen with results categorized into non-pharmacological and pharmacological interventions.

RESULTS

Initially, 271 articles were identified, which were narrowed to 28 articles with the use of a third search term related to sleep. Bibliography review yielded 4 additional articles. Data on interventions are limited by the heterogeneity of medical specialty, sample size, length of follow-up, and reliance on self-report. Non-pharmacological interventions including strategic scheduling and sleep hygiene may improve sleep and well-being. The available evidence, including randomized controlled trials, to support pharmacological interventions is limited.

CONCLUSIONS

Non-pharmacological approaches to mitigating fatigue and sleep deprivation have varying effectiveness to improve sleep for residents; however, data for pharmacological interventions is limited.

Objective Assessment of Sleep Patterns among Night-Shift Workers: A Scoping Review

In this scoping review of the literature, we identified the types and the parameters of objective measurements to assess sleep patterns among night-shift workers. We conducted a literature search using electronic databases for studies published from 1991 to 2020 and charted and summarized key information. We included 32 studies in the review. Polysomnography was used in 6 studies and wearable sleep detection devices were utilized in 26 studies. The duration of sleep assessment using the wearable devices ranged from 1 day to ≥4 weeks, and more than half of the studies collected data for >2 weeks. The majority of the studies used subjective questionnaires, such as the Karolinska Sleepiness Scale, Epworth Sleepiness Scale, and Pittsburgh Sleep Quality Index, in addition to objective sleep measurements. Total sleep time was the most common parameter, followed by sleep efficiency, sleep onset latency, and time or frequency of being awake. As the utilization of wearable devices to assess the sleep patterns of night-shift workers is expected to increase, further evaluation of device accuracy and precision, optimal data collection period, and key parameters is warranted.

Trends in Strategic Napping in Surgical Residents by Gender, Postgraduate Year, Work Schedule, and Clinical Rotation

OBJECTIVE

To identify surgical resident and clinical rotation attributes which predict on-shift napping through objectively measured sleep patterns and work schedules over a 2-month period.

DESIGN

In a cross-sectional study, participants provided schedules, completed the Epworth Sleepiness Scale (ESS), and wore sleep-tracking devices (Zulu watch) continuously for 8 weeks. Multiple linear regression predicted percent days with on-shift napping from resident and rotation characteristics.

SETTING

Greater Washington, DC area hospitals.

PARTICIPANTS

Twenty-two (n = 22) surgical residents rotating in at least 1 of 5 different clinical rotation categories.

RESULTS

Residents slept 6 hours within a 24-hour period (370 ± 129 minutes) with normal sleep efficiency (sleep efficiency (SE): 87.13% ± 7.55%). Resident ESS scores indicated excessive daytime sleepiness (11.64 ± 4.03). Ninety-five percent (n = 21) of residents napped on-shift. Residents napped on-shift approximately 32% of their working days and were most likely to nap when working between 23:00 and 05:00 hours. Earlier shift start times predicted less on-shift napping (B = -0.08, SE = 0.04, β = -2.40, t = -2.09, p = 0.05) while working more night shifts (B = 1.55, SE = 0.44, β = 4.12, t = 3.52, p = 0.003) and shifts over 24 hours (B = 1.45, SE = 0.55, β = 1.96, t = 2.63, p = 0.01) predicted more frequent on-shift napping.

CONCLUSIONS

Residents are taking advantage of opportunities to nap on-shift. Working at night seems to drive on-shift napping. However, residents still exhibit insufficient sleep and daytime sleepiness which could reduce competency and represent a safety risk to themselves and/or patients. These findings will help inform intervention strategies which are tailored to surgical residents using a biomathematical model of fatigue.

Implementation of interventions designed to promote healthy sleep and circadian rhythms in shiftworkers

Shiftwork is a significant risk factor for a host of negative health and safety outcomes, which have been at least partly attributed to disturbances of the circadian timing system. As a result, an entire sub-field of chronobiology has been devoted to developing and evaluating countermeasures for circadian misalignment, sleep disruption, fatigue, and other issues associated with shiftwork. Much of this research takes place under highly controlled laboratory conditions due to the necessity of accurately characterizing individual rhythms, both for intervention design and assessment of efficacy. Applied studies of interventions for shiftworkers are, by their nature, more complicated, often demonstrating less consistent findings. While this, in part, reflects execution under less rigorously controlled conditions, it may also stem from variability in implementation approaches. A systematic review of published studies (through May 2017) of interventions designed to enhance circadian health in shiftworkers was conducted to determine the frequency and quality of the assessment of implementation as well as barriers and enablers to implementation. A search of PubMed, PsychINFO, Web of Science, and CINAHL databases yielded a total of 5368 unique references. After a title and abstract screen, 323 proceeded to full-text review; 68 of those met final criteria for data extraction. Implementation was assessed to some degree in 60.3% of those 68 articles. Where it was assessed, the mean quality score on a scale from 1 to 5 (1 = very little, 3 = moderate, 5 = very in-depth) was 2.56. One or more enablers were identified in just 17 of the 68 studies (25.0%), and barriers in just 18 (26.5%). Implementation of these interventions is a critical but seldom-acknowledged component of their uptake and effectiveness, and we highly recommend that future shiftworker intervention research make an effort to incorporate formalized assessments of implementation and/or hybrid effectiveness-implementation approaches.

Mitigating fatigue on the flight deck: how is controlled rest used in practice?

Controlled Rest (CR) refers to a short, unscheduled, voluntary nap opportunity taken by pilots on the flight deck as a countermeasure to unanticipated fatigue in flight. This study explores the profile of CR use in a long-haul commercial airline. Forty-four pilots wore actiwatches and filled in an application-based sleep/work diary for approximately 2 weeks resulting in complete records from 239 flights. Timing of sleep periods and flight schedules were analyzed relative to home-base time. Pearson correlations were used to assess the influence of pilot demographics on CR use. A mixed-effects logistic regression was used to analyze the impact of schedule factors on CR. CR was taken on 46% (n = 110) of flights, with 80% (n = 106/133) of all CR attempts (accounting for multiple CR attempts on 23 flights) estimated by actigraphy to have successfully achieved sleep. Average sleep duration during successful rest periods was estimated as 31.7 ± 12.2 min. CR was more frequent on 2-pilot (69%, n = 83) vs. >2-pilot flights (23%, n = 27); return (60%, n = 71) vs. outbound flights (33%, n = 39); night (55%, n = 76) vs. day flights (34%, n = 34); and <10 h (63%, n = 80) vs. >10 h duration flights (27%, n = 30) (all p ≤ 0.001). There was no significant difference for direction of travel (eastbound: 51%, n = 57; westbound: 40%, n = 44; p = .059). Of note, 22% (n = 26) of augmented flights contained both CR and bunk rest. Data from this airline show that CR is most commonly used on flights with 2-pilot crews (<10 h duration) and nighttime flights returning to base. Future studies are required to determine the generalizability of these results to other airlines.

Physicians' working time restriction and its impact on patient safety: an integrative review

BACKGROUND

Although shift work is a part of the physicians' routine, there is controversy on the length of shifts and adequate rest for safe professional practice. If on the one hand long working hours might have negative impact on patient safety by interfering with the psychological and physical functioning of physicians, on the other shorter working hours might impair the safety of patients due to interference with the continuity of care.

OBJECTIVE

To analyze the impact of restrictions to physicians' working hours on patient safety.

METHOD

Integrative literature review in which we surveyed studies on restriction to physicians' working time and patient safety included in databases National Library of Medicine (PubMed) and Scientific Electronic Library Online (SciELO) until May 2018. Thirty-five studies which met the inclusion criteria were included.

RESULTS

Patient safety outcomes analyzed in the included studies were mortality, adverse events, continuity of care, in-hospital complications, readmission rate and length of stay at hospital. Restriction to working time was associated with variable impact on patient safety indicators, but often did not modify their performance.

CONCLUSION

Restrictions to physicians' working time did not always improved patient safety indicators. Focusing on interventions which only seek to limit the workload of physicians might be insufficient to bring consistent improvement to patient care.

Brief (<4 hr) sleep episodes are insufficient for restoring performance in first-year resident physicians working overnight extended-duration work shifts

STUDY OBJECTIVES

The Accreditation Council for Graduate Medical Education (ACGME) recently reinstated extended-duration (24-28 hr) work shifts (EDWS) for postgraduate year 1 (PGY-1) resident physicians. This study examined the relationship between overnight sleep duration during EDWS and subsequent "post-call" performance in PGY-1 resident physicians.

METHODS

Thirty-four PGY-1 resident physicians (23 males; 24-32 years) were studied between 2002 and 2004 during 3-week Q3 "on-call" rotation schedules in the Medical and Cardiac Intensive Care Units at Brigham and Women's Hospital in Boston. Daily sleep logs (validated by ambulatory polysomnography) were collected and the 10 min psychomotor vigilance task (PVT) was administered every ~6 hr during each EDWS. Generalized estimating equations were used to examine the relationship between overnight sleep duration and PVT performance "post-call" (0500-1900 hr). Postcall performance during EDWS was compared with sessions matched for time-of-day and weeks-into-schedule in the same resident physician during an intervention schedule that eliminated EDWS.

RESULTS

Resident physicians obtained an average of 1.6 ± 1.5 hr cumulative sleep overnight during EDWS (<4 hr on 92% of nights). PVT attentional failures were significantly reduced only after >4 hr sleep (p = 0.027 versus no sleep). Despite this apparent improvement, the odds of incurring >1 attentional failure were 2.72 times higher during postcall following >4 hr sleep compared with matched sessions during non-EDWS.

CONCLUSIONS

Even with >4 hr sleep overnight (8% of EDWS), performance remained significantly impaired. These findings suggest that even "strategic napping," a recommendation recently removed from ACGME guidelines, is insufficient to mitigate severe performance impairment introduced by extending duty beyond 16 hr.

Using a Single Daytime Performance Test to Identify Most Individuals at High-Risk for Performance Impairment during Extended Wake

We explored the predictive value of a neurobehavioral performance assessment under rested baseline conditions (evaluated at 8 hours awake following 8 hours of sleep) on neurobehavioral response to moderate sleep loss (evaluated at 20 hours awake two days later) in 151 healthy young participants (18-30 years). We defined each participant's response-to-sleep-loss phenotype based on the number of attentional failures on a 10-min visual psychomotor vigilance task taken at 20 hours awake (resilient: less than 6 attentional failures, n = 26 participants; non-resilient: 6 or more attentional failures, n = 125 participants). We observed that 97% of rested participants with 2 or more attentional failures (n = 73 of 151) and 100% of rested participants with 3 or more attentional failures (n = 57 of 151) were non-resilient after moderate sleep loss. Our approach can accurately identify a significant proportion of individuals who are at high risk for neurobehavioral performance impairment from staying up late with a single neurobehavioral performance assessment conducted during rested conditions. Additional methods are needed to predict the future performance of individuals who are not identified as high risk during baseline.

Fatigue Risk Management: The Impact of Anesthesiology Residents' Work Schedules on Job Performance and a Review of Potential Countermeasures

Long duty periods and overnight call shifts impair physicians' performance on measures of vigilance, psychomotor functioning, alertness, and mood. Anesthesiology residents typically work between 64 and 70 hours per week and are often required to work 24 hours or overnight shifts, sometimes taking call every third night. Mitigating the effects of sleep loss, circadian misalignment, and sleep inertia requires an understanding of the relationship among work schedules, fatigue, and job performance. This article reviews the current Accreditation Council for Graduate Medical Education guidelines for resident duty hours, examines how anesthesiologists' work schedules can affect job performance, and discusses the ramifications of overnight and prolonged duty hours on patient safety and resident well-being. We then propose countermeasures that have been implemented to mitigate the effects of fatigue and describe how training programs or practice groups who must work overnight can adapt these strategies for use in a hospital setting. Countermeasures include the use of scheduling interventions, strategic naps, microbreaks, caffeine use during overnight and extended shifts, and the use of bright lights in the clinical setting when possible or personal blue light devices when the room lights must be turned off. Although this review focuses primarily on anesthesiology residents in training, many of the mitigation strategies described here can be used effectively by physicians in practice.

Sleep and Alertness in a Duty-Hour Flexibility Trial in Internal Medicine

BACKGROUND

A purpose of duty-hour regulations is to reduce sleep deprivation in medical trainees, but their effects on sleep, sleepiness, and alertness are largely unknown.

METHODS

We randomly assigned 63 internal-medicine residency programs in the United States to follow either standard 2011 duty-hour policies or flexible policies that maintained an 80-hour workweek without limits on shift length or mandatory time off between shifts. Sleep duration and morning sleepiness and alertness were compared between the two groups by means of a noninferiority design, with outcome measures including sleep duration measured with actigraphy, the Karolinska Sleepiness Scale (with scores ranging from 1 [extremely alert] to 9 [extremely sleepy, fighting sleep]), and a brief computerized Psychomotor Vigilance Test (PVT-B), with long response times (lapses) indicating reduced alertness.

RESULTS

Data were obtained over a period of 14 days for 205 interns at six flexible programs and 193 interns at six standard programs. The average sleep time per 24 hours was 6.85 hours (95% confidence interval [CI], 6.61 to 7.10) among those in flexible programs and 7.03 hours (95% CI, 6.78 to 7.27) among those in standard programs. Sleep duration in flexible programs was noninferior to that in standard programs (between-group difference, -0.17 hours per 24 hours; one-sided lower limit of the 95% confidence interval, -0.45 hours; noninferiority margin, -0.5 hours; P = 0.02 for noninferiority), as was the score on the Karolinska Sleepiness Scale (between-group difference, 0.12 points; one-sided upper limit of the 95% confidence interval, 0.31 points; noninferiority margin, 1 point; P<0.001). Noninferiority was not established for alertness according to the PVT-B (between-group difference, -0.3 lapses; one-sided upper limit of the 95% confidence interval, 1.6 lapses; noninferiority margin, 1 lapse; P = 0.10).

CONCLUSIONS

This noninferiority trial showed no more chronic sleep loss or sleepiness across trial days among interns in flexible programs than among those in standard programs. Noninferiority of the flexible group for alertness was not established. (Funded by the National Heart, Lung, and Blood Institute and American Council for Graduate Medical Education; ClinicalTrials.gov number, NCT02274818.).

Adapting Maslow's Hierarchy of Needs as a Framework for Resident Wellness

ISSUE

Burnout in graduate medical education is pervasive and has a deleterious impact on career satisfaction, personal well-being, and patient outcomes. Interventions in residency programs have often addressed isolated contributors to burnout; however, a more comprehensive framework for conceptualizing wellness is needed.

EVIDENCE

In this article the authors propose Maslow's hierarchy of human needs (physiologic, safety, love/belonging, esteem, and self-actualization) as a potential framework for addressing wellness initiatives. There are numerous contributors to burnout among physician-trainees, and programs to combat burnout must be equally multifaceted. A holistic approach, considering both the trainees personal and professional needs, is recommended. Maslow's Needs can be adapted to create such a framework in graduate medical education. The authors review current evidence to support this model.

IMPLICATIONS

This work surveys current interventions to mitigate burnout and organizes them into a scaffold that can be used by residency programs interested in a complete framework to supporting wellness.

The effects of extended nap periods on cognitive, physiological and subjective responses under simulated night shift conditions

Extended nap opportunities have been effective in maintaining alertness in the context of extended night shifts (+12 h). However, there is limited evidence of their efficacy during 8-h shifts. Thus, this study explored the effects of extended naps on cognitive, physiological and perceptual responses during four simulated, 8-h night shifts. In a laboratory setting, 32 participants were allocated to one of three conditions. All participants completed four consecutive, 8-h night shifts, with the arrangements differing by condition. The fixed night condition worked from 22h00 to 06h00, while the nap early group worked from 20h00 to 08h00 and napped between 00h00 and 03h20. The nap late group worked from 00h00 to 12h00 and napped between 04h00 and 07h20. Nap length was limited to 3 hours and 20 minutes. Participants performed a simple beading task during each shift, while also completing six to eight test batteries roughly every 2 h. During each shift, six test batteries were completed, in which the following measures were taken. Performance indicators included beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. Physiological measures included heart rate and tympanic temperature, whereas subjective sleepiness and reported sleep length and quality while outside the laboratory constituted the self reported measures. Both naps reduced subjective sleepiness but did not alter the circadian and homeostatic-related changes in cognitive and physiological measures, relative to the fixed night condition. Additionally, there was evidence of sleep inertia following each nap, which resulted in transient reductions in certain perceptual cognitive performance measures. The present study suggested that there were some benefits associated with including an extended nap during 8-h night shifts. However, the effects of sleep inertia need to be effectively managed to ensure that post-nap alertness and performance is maintained.

Sleep and Alertness in Medical Interns and Residents: An Observational Study on the Role of Extended Shifts

Study Objectives

Fatigue from sleep loss is a risk to physician and patient safety, but objective data on physician sleep and alertness on different duty hour schedules is scarce. This study objectively quantified differences in sleep duration and alertness between medical interns working extended overnight shifts and residents not or rarely working extended overnight shifts.

Methods

Sleep-wake activity of 137 interns and 87 PGY-2/3 residents on 2-week Internal Medicine and Oncology rotations was assessed with wrist-actigraphy. Alertness was assessed daily with a brief Psychomotor Vigilance Test (PVT) and the Karolinska Sleepiness Scale.

Results

Interns averaged 6.93 hours (95% confidence interval [CI] 6.84-7.03 hours) sleep per 24 hours across shifts, significantly less than residents not working overnight shifts (7.18 hours, 95% CI 7.06-7.30 hours, p = .007). Interns obtained on average 2.19 hours (95% CI 2.02-2.36 hours) sleep during on-call nights (17.5% obtained no sleep). Alertness was significantly lower on mornings after on-call nights compared to regular shifts (p < .001). Naps between 9 am and 6 pm on the first day post-call were frequent (90.8%) and averaged 2.84 hours (95% CI 2.69-3.00 hours), but interns still slept 1.66 hours less per 24 hours (95% CI 1.56-1.76 hours) compared to regular shift days (p < .001). Sleep inertia significantly affected alertness in the 60 minutes after waking on-call.

Conclusions

Extended overnight shifts increase the likelihood of chronic sleep restriction in interns. Reduced levels of alertness after on-call nights need to be mitigated. A systematic comparison of sleep, alertness, and safety outcomes under current and past duty hour rules is encouraged.

What Is Known: Examining the Empirical Literature in Resident Work Hours Using 30 Influential Articles

BACKGROUND

Examining influential, highly cited articles can show the advancement of knowledge about the effect of resident physicians' long work hours, as well as the benefits and drawbacks of work hour limits.

OBJECTIVE

A narrative review of 30 articles, selected for their contribution to the literature, explored outcomes of interest in the research on work hours-including patient safety, learning, and resident well-being.

METHODS

Articles were selected from a comprehensive review. Citation volume, quality, and contribution to the evolving thinking on work hours and to the Accreditation Council for Graduate Medical Education standards were assessed.

RESULTS

Duty hour limits are supported by the scientific literature, particularly limits on weekly hours and reducing the frequency of overnight call. The literature shows declining hours and call frequency over 4 decades of study, although the impact on patient safety, learning, and resident well-being is not clear. The review highlighted limitations of the scientific literature on resident hours, including small samples and reduced generalizability for intervention studies, and the inability to rule out confounders in large studies using administrative data. Key areas remain underinvestigated, and accepted methodology is challenged when assessing the impact of interventions on the multiple outcomes of interest.

CONCLUSIONS

The influential literature, while showing the beneficial effect of work hour limits, does not answer all questions of interest in determining optimal limits on resident hours. Future research should use methods that permit a broader, collective examination of the multiple, often competing attributes of the learning environment that collectively promote patient safety and resident learning and well-being.

A 30-Minute, but Not a 10-Minute Nighttime Nap is Associated with Sleep Inertia

STUDY OBJECTIVES

To assess sleep inertia following 10-min and 30-min naps during a simulated night shift.

METHODS

Thirty-one healthy adults (aged 21-35 y; 18 females) participated in a 3-day laboratory study that included one baseline (BL) sleep (22:00-07:00) and one experimental night involving randomization to either: total sleep deprivation (NO-NAP), a 10-min nap (10-NAP) or a 30-min nap (30-NAP). Nap opportunities ended at 04:00. A 3-min psychomotor vigilance task (PVT-B), digit-symbol substitution task (DSST), fatigue scale, sleepiness scale, and self-rated performance scale were undertaken pre-nap (03:00) and at 2, 17, 32, and 47 min post-nap.

RESULTS

The 30-NAP (14.7 ± 5.7 min) had more slow wave sleep than the 10-NAP (0.8 ± 1.5 min; P < 0.001) condition. In the NO-NAP condition, PVT-B performance was worse than pre-nap (4.6 ± 0.3 1/sec) at 47 min post-nap (4.1 ± 0.4 1/sec; P < 0.001). There was no change across time in the 10-NAP condition. In the 30-NAP condition, performance immediately deteriorated from pre-nap (4.3 ± 0.3 1/sec) and was still worse at 47 min post-nap (4.0 ± 0.5 1/sec; P < 0.015). DSST performance deteriorated in the NO-NAP (worse than pre-nap from 17 to 47 min; P < 0.008), did not change in the 10-NAP, and was impaired 2 min post-nap in the 30-NAP condition (P = 0.028). All conditions self-rated performance as better than pre-nap for all post-nap test points (P < 0.001).

CONCLUSIONS

This study is the first to show that a 10-min (but not a 30-min) nighttime nap had minimal sleep inertia and helped to mitigate short-term performance impairment during a simulated night shift. Self-rated performance did not reflect objective performance following a nap.