The effects of bright light treatment on affective symptoms in people with dementia: a 24-week cluster randomized controlled trial.

BACKGROUND: The majority of people with dementia have behavioral and psychological symptoms of dementia (BPSD), including depression, anxiety and agitation. These may be elicited or aggravated by disrupted circadian rhythms. Bright light treatment (BLT) is a promising non-pharmacological approach to the management of BPSD, but previous research has yielded mixed results. METHODS: Eight nursing home dementia units (1 unit = 1 cluster) with 78 patients were invited to participate in a cluster randomized controlled trial from September 2017 to April 2018 investigating the effects of BLT on sleep and circadian rhythms (primary outcome) and BPSD (secondary outcome). Ceiling mounted LED-panels were installed in the intervention group (four units), providing light at 1000 lx and 6000 K (vertically at 1.2 m) between 10 a.m. and 3 p.m., with lower values in the mornings and evenings. Standard indoor light was used in the control group (four units). BPSD were assessed with The Cornell Scale for Depression in Dementia (CSDD) and the Neuropsychiatric Inventory Nursing Home Version (NPI-NH). Data collection took place at baseline and after 8, 16 and 24 weeks. Multilevel regression models with and without false discovery rate correction were used for the analysis, with baseline values and dementia stage entered as covariates. RESULTS: Sixty-nine patients were included in the study at baseline. Compared to the control group, the intervention group had a larger reduction on the composite scores of both the CSDD (95% CI = - 6.0 - - 0.3) and the NPI-NH (95% CI = - 2.2 - - 0.1), as well as on the NPI-NH Affect sub-syndrome, and the CSDD Mood related signs sub-scale at follow-up after 16 weeks. With FDR correction, the group difference was significant on the CSDD Mood related signs sub-scale (95% CI = - 2.7 - - 0.8) and the NPI-NH Affect sub-syndrome (95% CI = - 1.6 - - 0.2). No differences were found between conditions at weeks 8 or 24. CONCLUSION: Compared to the control condition, affective symptoms were reduced after 16 weeks in the group receiving BLT, suggesting BLT may be beneficial for nursing home patients with dementia. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03357328 . Retrospectively registered on November 29, 2017.

Ambient bright light treatment improved proxy-rated sleep but not sleep measured by actigraphy in nursing home patients with dementia: a placebo-controlled randomised trial.

BACKGROUND: Up to 70% of nursing home patients with dementia suffer from sleep problems. Light is the main zeitgeber to the circadian system and thus has a fundamental impact on sleep-wake behaviour. Low indoor light levels in nursing homes have been reported, and in combination with age-related reductions in light sensitivity, insufficient light exposure is likely to contribute to sleep problems in this population. Increasing daytime light exposure using bright light treatment (BLT) may represent a feasible non-pharmacological treatment for sleep problems in nursing home patients with dementia. METHODS: The present study reports on sleep outcomes, which are the primary outcomes of the DEM.LIGHT trial (Therapy Light Rooms for Nursing Home Patients with Dementia- Designing Diurnal Conditions for Improved Sleep, Mood and Behavioural Problems), a 24-week cluster-randomised placebo-controlled trial including 8 nursing home units and 69 resident patients. The intervention comprised ambient light of 1000 lx and 6000 K from 10:00 to 15:00, with gradually increasing and decreasing light levels prior to and following this interval, using ceiling mounted light-fixtures and light emitting diode technology. The placebo condition had continuous standard light levels (150-300 lx, ~ 3000 K). Sleep was assessed at baseline and follow-up at week 8, 16, and 24, using the proxy-rated Sleep Disorder Inventory (SDI) and actigraphy (Actiwatch II, Philips Respironics). Mixed linear models were used to evaluate intervention effects, adjusting for relevant covariates such as age, gender, number of drugs, severity of dementia, eye disease, and estimated light exposure. RESULTS: Sleep as measured by the SDI was significantly improved in the intervention group compared to the control group from baseline to week 16 (B = - 0.06, 95% CI -0.11 - -0.01, p < .05) and from baseline to week 24 (B = - 0.05, 95% CI -0.10 - -0.01, p < .05). There was no effect according to the SDI at week 8 and no significant effects in terms of actigraphically measured sleep. CONCLUSIONS: Proxy-rated sleep improved among nursing home patients with dementia following 16 and 24 weeks of BLT. These improvements were not corroborated by actigraphy recordings. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03357328 . Registered 29 November 2017 - Retrospectively registered.

Short sleep duration and high exposure to quick returns are associated with impaired everyday memory in shift workers.

PURPOSE: To investigate the relationship between self-reported everyday memory problems the last month, and: (a) shift work schedule, (b) night shifts and quick returns worked the last year, and (c) sleep duration the last month. METHODS: In all, 1,275 nurses completed the Everyday Memory Questionnaire - revised, and answered questions about shift work exposure and sleep duration. We performed multiple linear regression analyses with memory score as dependent variable, and the shift work exposure variables as well as sleep duration as predictors, while adjusting for potential confounders. FINDINGS: High exposure to quick returns (ß = .10, p < .05) and short sleep duration (ß = .10, p < .05) were both positively associated with memory problems, whereas shift work schedule, long sleep duration, night shift exposure, and low and moderate exposure to quick returns were not. DISCUSSION: Frequent insufficient time for rest between shifts as well as short sleep was associated with poorer everyday memory.

Role of nocturnal light intensity on adaptation to three consecutive night shifts: a counterbalanced crossover study.

OBJECTIVES: To investigate how a standard ceiling mounted light-emitting diode (LED)-based bright light intervention affected alertness and neurobehavioural performance during three consecutive simulated night shifts, and timing of circadian rhythm after the shifts. METHODS: Twenty seven participants (20 females, 21.4±2.1 years; mean±SD) worked three consecutive night shifts (23:00-07:00) under a full-spectrum (4000 K) bright light (900 lx) and a standard light (90 lx) condition in a counterbalanced crossover design (separated by 4 weeks). Subjective alertness (Karolinska Sleepiness Scale) and neurobehavioural performance (Psychomotor Vigilance Task and Digit Symbol Substitution Test) were assessed five times during each shift. Salivary dim-light melatonin onset (DLMO) was assessed before and after the shifts. The simulated night shifts were conducted in a laboratory while the participants slept at home. RESULTS: Subjective alertness and neurobehavioural performance deteriorated during the night shifts in both light conditions. However, bright light significantly reduced alertness and performance decrements as compared with standard light. For a subset of the participants, DLMO was delayed by a mean of 3:17±0:23 (mean±SEM) hours after three night shifts in bright light and by 2:06±0:15 hours in standard light, indicating that bright light causes larger phase delay. CONCLUSION: Bright light improved performance and alertness during simulated night shifts and improved adaptation to night work. Bright light administered by ceiling mounted LED luminaires has the potential to improve adaptation to night work and reduce the risk of accidents and injuries among night workers. TRIAL REGISTRATION NUMBER: NCT03203538.

Unravelling the Prospective Associations Between Mixed Anxiety-Depression and Insomnia During the Course of Cognitive Behavioral Therapy.

OBJECTIVE: Previous studies have suggested that there is a reciprocal relationship between anxiety/depression and insomnia. However, little is known about the prospective relationships between these constructs across the course of cognitive behavioral therapy (CBT). The aim of the study was to examine these relationships in clients who received short-term CBT in a primary care setting. METHODS: A total of 653 clients (mean [SD] age = 37.8 [12.9], 26.4% men) with mild to moderate levels of anxiety and depression and a treatment duration of at least 7 weeks were included for analyses. The clients completed questionnaires measuring mixed anxiety-depression (MAD - Patient Health Questionnaire Anxiety and Depression Scale) and insomnia (3 items derived from the Karolinska Sleep Questionnaire representing core DSM-V criteria) on a session-to-session basis. The data were analyzed using latent growth curve models and random intercept cross-lagged panel models. RESULTS: The results of the latent growth curve models showed that there was a significant decrease in both MAD (cubic slope; B = .002, p < .001, quadratic slope; B = .036, p < .001, linear slope; B = -.205, p < .001) and insomnia (linear slope; B = -.080, p < .001) across treatment. A strong correlation (r = .838, p < .001) between the linear slopes indicated co-occurring change processes. The cross-lagged panel model showed that insomnia significantly predicted MAD at the subsequent measurements (B = .190, p < .001), but not vice versa (B = .252, p = .343). CONCLUSIONS: Changes in MAD and insomnia are co-occurring processes during the course of CBT. Changes in insomnia predicted prospectively changes in MAD, but not vice versa. Targeting insomnia in the context of brief CBT in clients with mild to moderate anxiety and depression may therefore further reduce not only symptoms of insomnia but also symptoms of anxiety and depression.

The effects of bright light treatment on subjective and objective sleepiness during three consecutive night shifts among hospital nurses - a counter-balanced placebo-controlled crossover study.

Objectives The objective was to investigate effects of timed bright light treatment on subjective and objective measures of sleepiness during three consecutive night shifts among hospital nurses. Methods Thirty-five nurses were exposed to bright light (10,000 lux) and red dim light (100 lux) during three consecutive night shifts in a counter-balanced crossover trial lasting nine days, which included three days before and three days after the three night shifts. Light exposure for 30 minutes was scheduled between 02:00-03:00 hours on night 1, and thereafter delayed by one hour per night in order to delay the circadian rhythm. Subjective sleepiness was measured daily (heavy eyelids, reduced performance) and every second hour while awake (Karolinska Sleepiness Scale, KSS). Objective sleepiness (Psychomotor Vigilance Task, PVT) was measured at 05:00 hours during each night shift. Beyond nocturnal light exposure on the night shifts, no behavioral restrictions or recommendations were given at or off work. Results Bright light treatment significantly reduced heavy eyelids during night shifts. However, results on KSS and PVT were unaffected by bright light. There were no differences in subjective sleepiness during the three days following the night shifts. Conclusions This bright light treatment protocol did not convincingly reduce sleepiness among nurses during three consecutive night shifts. Nor did bright light impede the readaptation back to a day-oriented rhythm following the night shift period. Too few consecutive night shifts, inappropriate timing of light, and possible use of other countermeasures are among the explanations for the limited effects of bright light in the present study.

Stability and Change of the Personality Traits Languidity and Flexibility in a Sample of Nurses: A 7-8 Years Follow-Up Study.

The traits languidity (tendency to become tired/sleepy upon losing sleep) and flexibility (ability to sleep and work at odd times) have been implicated in shift work tolerance. However, there is a dearth of knowledge about their temporal stability. The aim of the present study was to explore these traits during a long follow-up (FU) period and identify factors related to potential changes in trait scores over time. In all, 1,652 nurses completed the Circadian Type Inventory-revised (CTI-r), which measures languidity and flexibility, at both 2008/2009 (baseline, BL) and again in 2016 (FU). The latent scores of these two constructs at BL, in addition to age, sex, childcare responsibility, marital status, night work status, and insomnia status, were regressed on the corresponding latent scores at follow-up using a structural equation modeling (SEM) approach. Stability was found for both languidity (rho = 0.59) and flexibility (rho = 0.58). Both composite scores declined significantly from baseline (20.62 and 12.48) to follow-up (19.96 and 11.77). Languidity at baseline was positively associated with languidity at follow-up (ß = 0.89, p < 0.009). Undertaking childcare responsibility between baseline and follow-up was inversely related to languidity at follow-up (ß = -0.09, p < 0.05). Starting night work was positively related to languidity at follow-up (ß = 0.06, p < 0.05). Developing insomnia between baseline and follow-up (ß = 0.15, p < 0.05) was positively, whereas remitting from insomnia during the same period was negatively (ß = -0.11, p < 0.01) associated with languidity at follow-up. Flexibility at baseline was positively associated with flexibility at follow-up (ß = 0.64, p < 0.05). Having childcare responsibility at baseline, but not at follow-up was inversely related to flexibility at follow-up (ß = -0.05 p < 0.05). Becoming cohabitant with a partner between baseline and follow-up (ß = -0.07, p < 0.05) was negatively associated with flexibility at follow-up. Starting night work between baseline and follow-up (ß = 0.17, p < 0.01) and reporting night work at both baseline and follow-up (ß = 0.18, p < 0.01) were both positively associated with flexibility at follow-up, whereas stopping working nights was negatively (ß = -0.09, p < 0.05), associated with flexibility at follow-up. The personality traits languidity and flexibility show fairly high stability, albeit the mean scores were significantly reduced during the 7-8 years follow-up period. The results suggest that these personality traits are partly modifiable.

Changes in work schedule affect the prevalence of shift work disorder among Norwegian nurses - a two year follow-up study.

This study aimed to explore how changes in the work schedule would affect the prevalence of Shift Work Disorder (SWD) over time. Two-year follow-up data from 1076 nurses participating in the longitudinal SUrvey of Shift work, Sleep and Health among Norwegian nurses (SUSSH) were included in the study. The questionnaires included measures of work-related factors, i.e., work schedule and numbers of night shifts and quick returns (QRs) worked the last year, as well as questions related to SWD according to the ICSD-3 diagnostic criteria at both baseline and at 2-year follow-up. Data were analyzed with paired samples t-tests, chi-square tests, and logistic regression analyses adjusting for sex and age. Terminating night work was the strongest predictor for recovering from SWD from baseline to follow-up (OR 10.91, 95% CI 6.11-19.46). Additionally, changing the work schedule from day work to night work from baseline to follow-up was the strongest predictor for developing SWD in the same period (OR 4.75, 95% CI 2.39-9.47). Reductions in number of nights (more than 10) and QRs (more than 10) worked the last year were associated with recovering from SWD between baseline and follow-up. Nurses who recovered from SWD had significantly reduced the mean number of night shifts worked the last year from 32.3 at baseline to 20.4 at follow-up (p = .001). Furthermore, an increase of more than 10 nights or more than 10 QRs worked the last year between baseline and follow-up predicted developing SWD. Nurses developing SWD between baseline and follow-up had significantly increased the mean number of nights worked the last year from 25.8 at baseline to 31.0 at follow-up (p =-.043). Changes in night work exposure were the strongest predictors for both recovering from or developing SWD from baseline to follow-up. Reducing exposure to night work and QRs were associated with recovering from SWD and increasing exposure to night work and QRs were associated with developing SWD. The results imply that unfavorable work schedules play a role in the development of sleep problems among nurses. These results may be useful when designing healthy working schedules.

Light interventions and sleep, circadian, behavioral, and psychological disturbances in dementia: A systematic review of methods and outcomes.

Dementia is a devastating disease with a global impact, and there is an urgent need for effective interventions to alleviate the accompanying disturbances in behavior, mood, sleep, and circadian rhythms. Bright light treatment (BLT) is a promising non-pharmacological intervention; however, studies have yielded conflicting results. This systematic review provides a comprehensive overview of the effect of BLT in dementia, with a specific focus on how study characteristics might have affected the available results. The included studies were small and comprised time-limited interventions and follow-ups. Light values, adherence to treatment, and time of year were not consistently reported. Varying designs, methods, and population characteristics such as age, gender, dementia diagnosis, circadian phase, and baseline symptoms may have moderated the outcomes and affected review results. The use of crossover designs and too high illumination as placebo lights might have nullified positive effects of BLT. Because some studies had negative outcomes after ambient BLT with high amounts of short wavelengths, more modest light levels should be further investigated. Employing rigorous designs and detailed reporting of intervention characteristics, i.e., the illumination, correlated color temperature, timing, and duration of light utilized, are of utmost importance to establish the optimal treatment approach in this population. Systematic review registration number: PROSPERO CRD42017051004.

An Actigraphy-Based Validation Study of the Sleep Disorder Inventory in the Nursing Home.

Background: Disrupted sleep is common among nursing home patients with dementia and is associated with increased agitation, depression, and cognitive impairment. Detecting and treating sleep problems in this population are therefore of great importance, albeit challenging. Systematic observation and objective recordings of sleep are time-consuming and resource intensive and self-report is often unreliable. Commonly used proxy-rated scales contain few sleep items, which affects the reliability of the raters' reports. The present study aimed to adapt the proxy-rated Sleep Disorder Inventory (SDI) to a nursing home context and validate it against actigraphy. Methods: Cross-sectional study of 69 nursing home patients, 68% women, mean age 83.5 (SD 7.1). Sleep was assessed with the SDI, completed by nursing home staff, and with actigraphy (Actiwatch II, Philips Respironics). The SDI evaluates the frequency, severity, and distress of seven sleep-related behaviors. Internal consistency of the SDI was evaluated by Cronbach's alpha. Spearman correlations were used to evaluate the convergent validity between actigraphy and the SDI. Test performance was assessed by calculating the sensitivity, specificity, and predictive values, and by ROC curve analyses. The Youden's Index was used to determine the most appropriate cut-off against objectively measured sleep disturbance defined as <6 h nocturnal total sleep time (TST) during 8 h nocturnal bed rest (corresponding to SE <75%). Results: The SDI had high internal consistency and convergent validity. Three SDI summary scores correlated moderately and significantly with actigraphically measured TST and wake-after-sleep-onset. A cut-off score of five or more on the SDI summed product score (sum of the products of the frequency and severity of each item) yielded the best sensitivity, specificity, predictive values, and Youden's Index. Conclusion: We suggest a clinical cut-off for the presence of disturbed sleep in institutionalized dementia patients to be a SDI summed product score of five or more. The results suggest that the SDI can be clinically useful for the identification of disrupted sleep when administered by daytime staff in a nursing home context. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03357328.

The Association Between Shift Work and Immunological Biomarkers in Nurses.

Objectives: Shift work is associated with several negative health effects. The underlying pathophysiological mechanisms are unclear, but low-grade inflammation has been suggested to play a role. This project aimed to determine whether levels of immunological biomarkers differ depending on work schedule, self-reported sleep duration, self-reported sleep quality, and presence of shift work disorder (study 1). Furthermore, we aimed to determine whether these biomarkers differ after a night of sleep vs. at the end of a night or a day shift (study 2). Methods: In study 1, 390 nurses provided blood samples after a night of sleep with the dried blood spot method. In study 2, a subset of 55 nurses also provided blood samples after a day shift and after a night shift. The following biomarkers were measured: interleukin-1alpha, interleukin-1beta, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-13, monocyte chemoattractant protein-1, interferon-gamma, and tumor necrosis factor-alpha. Multiple linear regressions with adjustment for age, sex and body mass index (study 1) and ANOVAs with repeated measures (study 2) were conducted. Results: In study 1, neither work schedule, number of night shifts, number of quick returns (<11 h between consecutive shifts), sleep duration, poor sleep quality, nor shift work disorder were systematically associated with most of these biomarkers. Compared with day only work, day-evening work was associated with higher levels of IL-1alpha and IL-13, quick returns were associated with higher levels of IL-1beta and MCP-1, short sleep duration (<6 h) was associated with lower levels of IL-1beta and higher levels of TNF-alpha, and long sleep duration (8+ h) was associated with higher levels of IL-13. In study 2, IL-1beta levels were higher (large effect size) both after a day shift (14% increase) and a night shift (75% increase) compared with levels after a night of sleep. Similarly, TNF-alpha levels were higher (moderate-large effect size) after a day shift (50% increase) compared to after a night of sleep. In contrast, MCP-1 levels were lower (large effect size) both after a day shift (22% decrease) and a night shift (12% decrease) compared with after a night of sleep. Conclusions: We found some indications that shift work influenced immunological biomarkers. The results should be interpreted with caution due to limitations, e.g., related to the sampling procedure and to low levels of biomarkers in the blood samples.

Alerting and Circadian Effects of Short-Wavelength vs. Long-Wavelength Narrow-Bandwidth Light during a Simulated Night Shift.

Light can be used to facilitate alertness, task performance and circadian adaptation during night work. Novel strategies for illumination of workplaces, using ceiling mounted LED-luminaires, allow the use of a range of different light conditions, altering intensity and spectral composition. This study (ClinicalTrials.gov Identifier NCT03203538) investigated the effects of short-wavelength narrow-bandwidth light (λmax = 455 nm) compared to long-wavelength narrow-bandwidth light (λmax = 625 nm), with similar photon density (~2.8 × 1014 photons/cm2/s) across light conditions, during a simulated night shift (23:00-06:45 h) when conducting cognitive performance tasks. Light conditions were administered by ceiling mounted LED-luminaires. Using a within-subjects repeated measurements study design, a total of 34 healthy young adults (27 females and 7 males; mean age = 21.6 years, SD = 2.0 years) participated. The results revealed significantly reduced sleepiness and improved task performance during the night shift with short-wavelength light compared to long-wavelength light. There was also a larger shift of the melatonin rhythm (phase delay) after working a night shift in short-wavelength light compared to long-wavelength light. Participants' visual comfort was rated as better in the short-wavelength light than the long-wavelength light. Ceiling mounted LED-luminaires may be feasible to use in real workplaces, as these have the potential to provide light conditions that are favorable for alertness and performance among night workers.

Blue-Enriched White Light Improves Performance but Not Subjective Alertness and Circadian Adaptation During Three Consecutive Simulated Night Shifts.

Use of blue-enriched light has received increasing interest regarding its activating and performance sustaining effects. However, studies assessing effects of such light during night work are few, and novel strategies for lighting using light emitting diode (LED) technology need to be researched. In a counterbalanced crossover design, we investigated the effects of a standard polychromatic blue-enriched white light (7000 K; ∼200 lx) compared to a warm white light (2500 K), of similar photon density (∼1.6 × 1014 photons/cm2/s), during three consecutive simulated night shifts. A total of 30 healthy participants [10 males, mean age 23.3 (SD = 2.9) years] were included in the study. Dependent variables comprised subjective alertness using the Karolinska Sleepiness Scale, a psychomotor vigilance task (PVT) and a digit symbol substitution test (DSST), all administered at five time points throughout each night shift. We also assessed dim-light melatonin onset (DLMO) before and after the night shifts, as well as participants' opinion of the light conditions. Subjective alertness and performance on the PVT and DSST deteriorated during the night shifts, but 7000 K light was more beneficial for performance, mainly in terms of fewer errors on the PVT, at the end of the first- and second- night shift, compared to 2500 K light. Blue-enriched light only had a minor impact on PVT response times (RTs), as only the fastest 10% of the RTs were significantly improved in 7000 K compared to 2500 K light. In both 7000 and 2500 K light, the DLMO was delayed in those participants with valid assessment of this parameter [n = 20 (69.0%) in 7000 K light, n = 22 (78.6%) in 2500 K light], with a mean of 2:34 (SE = 0:14) and 2:12 (SE = 0:14) hours, respectively, which was not significantly different between the light conditions. Both light conditions were positively rated, although participants found 7000 K to be more suitable for work yet evaluated 2500 K light as more pleasant. The data indicate minor, but beneficial, effects of 7000 K light compared to 2500 K light on performance during night work. Circadian adaptation did not differ significantly between light conditions, though caution should be taken when interpreting these findings due to missing data. Field studies are needed to investigate similar light interventions in real-life settings, to develop recommendations regarding illumination for night workers. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03203538.

A longitudinal study on the association between quick returns and occupational accidents.

Objective This study aimed to investigate how change in the number of quick returns [(QR) <11 hours between consecutive shifts] longitudinally is associated with risk of occupational accidents among nurses. Methods Two-year follow-up data from 1692 nurses participating in the Survey of Shiftwork, Sleep and Health among Norwegian nurses (SUSSH) (mean age 40.2, standard deviation 8.3 years, 91% female) were used. Negative binomial regression analyses were conducted to investigate the association between changes in the number of QR after two years and occupational accidents, controlling for demographics, work factors, and occupational accidents at baseline. Results An increase from having no or a moderate number of QR (1-34 per year) from baseline to the two-year follow-up assessment was associated with an increased risk of occupational accidents, compared to experiencing no change in the number of QR. Those with a moderate number of QR at baseline who experienced an increase after two years had an increased risk of causing harm to patients/others [incident rate ratio (IRR) 8.49, 95% confidence interval (CI) 2.79-25.87] and equipment at work (IRR 2.89, 95% CI 1.13-7.42). Those who had many QR (>34 per year) at baseline but experienced a reduction after two years had a reduced risk of causing harm to themselves (IRR 0.35, 95% CI 0.16-0.73) and patients/others (IRR 0.27, 95% CI 0.12-0.59). Conclusion A fairly consistent pattern was demonstrated in which changes in the number of QR over the two-year follow-up period was associated with a corresponding change in the risk of occupational accidents.

The Effects of Sleep Deprivation on Soccer Skills.

Many athletes sleep poorly due to stress, travel, and competition anxiety. In the present study, we investigated the effects of sleep deprivation on soccer skills (juggling, dribbling, ball control, continuous kicking, 20 and 40 m sprint, and 30 m sprint with changes of direction). In all, 19 male junior soccer players (14-19 years old) were recruited and participated in a cross-balanced experimental study comprising two conditions; habitual sleep and 24 hours sleep deprivation. In both conditions, testing took place between 8 a.m. and 10 a.m. Order of tests was counterbalanced. Each test was conducted once or twice in a sequence repeated three times. The results revealed a negative effect of sleep deprivation on the continuous kicking test. On one test, 30 meter sprint with directional changes, a significant condition × test repetition interaction was found, indicating a steeper learning curve in the sleep deprived condition from Test 1 to Test 2 and a steeper learning curve in the rested condition from Test 2 to Test 3. The results are discussed in terms of limitations and strengths, and recommendations for future studies are outlined.

A Comparative Study of Sleep and Mood Between Young Elite Athletes and Age-Matched Controls.

BACKGROUND: Sleep and mood have seldom been compared between elite athletes and nonelite athletes, although potential differences suggest that physical activity may affect these parameters. This study aims to explore whether adolescent elite athletes differ from controls in terms of sleep, positive affect (PA) and negative affect (NA). METHODS: Forty-eight elite athletes and 26 controls participating in organized and nonorganized sport completed a questionnaire, and a 7-day sleep diary. RESULTS: On school days, the athletes and the controls who participated in organized and nonorganized sport differed in bedtime (22:46, 23:14, 23:42, P < .01), sleep onset (23:03, 23:27, 00:12, P < .01), and total sleep time (7:52, 8:00, 6:50, P < 01). During weekend, the athletes, the controls who participated in organized and nonorganized sport differed in bedtime (23:30, 00:04, 00:49, P < .01), sleep onset (23.42, 00:18, 01:13, P < .01), rise time (9:15, 9:47, 10:55, P < .01), sleep efficiency (95.0%, 94.2%, 90.0%, P < 05), and sleep onset latency (11.8, 18.0, 28.0 minutes, P < .01). Furthermore, the athletes reported less social jetlag (0:53) and higher score for PA (34.3) compared with the controls who participated in nonorganized sport (jetlag: 1:25, P < .05, PA: 29.8, P < .05). CONCLUSIONS: An almost dose-response association was found between weekly training hours, sleep, social jetlag and mood in adolescents.

Trajectories of sleepiness and insomnia symptoms in Norwegian nurses with and without night work and rotational work.

Numerous cross-sectional studies report high prevalence rates of sleepiness and insomnia in shift workers, but few longitudinal studies exist. We investigated trajectories of sleepiness and insomnia symptoms in a sample of Norwegian nurses across four measurements, spanning a total of four years (sleepiness) and five years (insomnia). The participants completed the Epworth Sleepiness Scale and the Bergen Insomnia Scale at each measurement instance. Latent growth curve models were used to analyse the data. Separate models examined night work (night work, entering and leaving night work) and rotational work (rotational work, entering and leaving rotational work) as predictors for trajectories of sleepiness and insomnia symptoms, respectively. Baseline values of sleepiness and insomnia were higher among rotational shift workers than among workers with fixed shifts (day or night). The results showed that night work throughout the period and entering night work during the period were not associated with different trajectories of sleepiness or insomnia symptoms, compared to not having night work. The same results were found for rotational work and entering rotational work, compared to not having rotational work. Leaving night work and leaving rotational work were associated with a decrease in sleepiness and insomnia symptoms, compared to staying in such work.

Sleep, circadian rhythms, and athletic performance.

Sleep deprivation and time of day are both known to influence performance. A growing body of research has focused on how sleep and circadian rhythms impact athletic performance. This review provides a systematic overview of this research. We searched three different databases for articles on these issues and inspected relevant reference lists. In all, 113 articles met our inclusion criteria. The most robust result is that athletic performance seems to be best in the evening around the time when the core body temperature typically is at its peak. Sleep deprivation was negatively associated with performance whereas sleep extension seems to improve performance. The effects of desynchronization of circadian rhythms depend on the local time at which performance occurs. The review includes a discussion of differences regarding types of skills involved as well as methodological issues.

Restricted use of electronic media, sleep, performance, and mood in high school athletes--a randomized trial.

OBJECTIVES: The study aims to evaluate whether 4 weeks with restricted use of electronic media after 22:00 affects sleep, athletic performance, cognitive performance, and mood in high school athletes. METHODS: Eighty-five athletes were randomized to either an intervention group (n = 44), who was instructed to not use any electronic media after 22:00, or a control condition (n = 41), where they could act as they preferred in terms of media use. Primary outcomes were sleep habits measured with a sleep diary. Secondary outcomes were (a) physical performance measured with a set of standardized tests (beep test, 20-m linear sprint, chin-up test, hanging sit-ups test, counter movement jump and sit-n-reach test); (b) cognitive performance (response time and response accuracy); and (c) positive and negative affect. Differences between groups were tested with mixed between-within subject analyses of variance. RESULTS AND CONCLUSIONS: Thirty-five and 40 of the athletes in the intervention and control group, respectively, completed the study. Results showed that restricted use of electronic media after 22:00 did not improve sleep habits, athletic performance, cognitive performance, or mood in a group of high school top athletes with already good sleep habits. However, these findings give us knowledge about sleep habits and performance in this population that is of importance when designing future studies.

Predictive Value of the SF-12 for Sickness Absence Because of Mental, Musculoskeletal, and Other Somatic Disorders.

OBJECTIVE: To investigate the predictive value of the 12-item short form (SF-12) for long-term sickness absence (LTSA) because of mental, musculoskeletal, and other somatic disorders. METHODS: In this cohort study with 2-year follow-up of 1381 nurses, baseline SF-12 scores were analyzed against registered mental, musculoskeletal, and other somatic LTSA during follow-up by logistic regression models. RESULTS: The SF-12 dimensions, general health, vitality, emotional role limitations, mental health, and social functioning, predicted mental LTSA. Physical functioning, bodily pain, and vitality predicted musculoskeletal LTSA, and physical role limitations, bodily pain, general health, and social functioning predicted other somatic LTSA. Positive predictive values were low, and negative predictive values were high. CONCLUSIONS: Different SF-12 dimensions predicted mental, musculoskeletal, and other somatic LTSA but did not identify nurses at high risk of mental, musculoskeletal, and other somatic LTSA.