Napping behaviour, daytime sleepiness, and arousal in high performance athletes and non-athlete controls

Napping offers a strategy to manage sleep, aid recovery and enhance performance in elite sport. However, relatively little research attention has focussed on the natural history of athlete napping or tested the widely held assumption that athlete napping is mainly a consequence of degraded night-time sleep. Within a sample of 158 team (n = 76) and individual (n = 80) sport athletes, and 82 non-athlete controls, we analysed napping behaviour in relation to sleep quality, daytime sleepiness, and pre-sleep somatic and cognitive arousal. There was no significant association between athlete/non-athlete status and the prevalence, frequency, or duration of naps. Comparisons of athlete nappers and non-nappers found no significant differences in sleep quantity or quality. While nap propensity was significantly related to higher daytime sleepiness, this influence was moderated or augmented by levels of pre-sleep cognitive arousal. For some nappers, those with higher levels of arousal may need to be sleepier than those with lower levels of arousal in order to successfully initiate daytime sleep. Approximately 50% of athletes did not nap. If the benefits of athlete napping are to be fully exploited, the needs of this substantial group for whom napping may be problematic should be recognised and addressed.

Altered Core Temperature and Salivary Melatonin in Athletes with a Cervical Spinal Cord Injury

Sleep disturbances are common in athletes with a cervical spinal cord injury (cSCI) and may be associated with circadian alterations. Therefore, the purpose of this study was to compare physiological circadian outputs between athletes with a cSCI and non-disabled controls (CON). Eight male wheelchair athletes with a cSCI and eight male CON (30±4 and 30±6 yrs, respectively) had their core body temperature (T_core), skin temperature (T_skin), and salivary melatonin measured during a 24 h period. In the cSCI group, daytime T_core was significantly lower (36.5 (0.2) vs 36.9 (0.3)°C; p=0.02) and time of the T_core sleep minimum was significantly earlier (23:56±00:46 vs 02:39 ± 02:57; p=0.04). The athletes with a cSCI had significantly lower T_core values during the beginning of the night compared with the CON group, but their T_core increased at a greater rate, thereafter, indicated by a significant time/group interaction (p=0.04). Moreover, the cSCI group did not display a salivary melatonin response and exhibited significantly lower concentrations at 22:00 (p=0.01) and 07:00 (p=0.01) compared with the CON group. Under natural living conditions, athletes with a cSCI displayed circadian changes in the T_core rhythm and nocturnal melatonin production.

Sleep extension and metabolic health in male overweight/obese short sleepers: A randomised controlled trial

While limited evidence suggests that longer sleep durations can improve metabolic health in habitual short sleepers, there is no consensus on how sustained sleep extension can be achieved. A total of 18 men (mean [SD] age 41 [ 9] years), who were overweight/obese (mean [SD] body mass index 30 [3] kg/m² ) and short sleepers at increased risk of type 2 diabetes were randomised to a 6-week sleep-extension programme based on cognitive behavioural principles (n = 10) or a control (n = 8) group. The primary outcome was 6-week change in actigraphic total sleep time (TST). Fasting plasma insulin, insulin resistance (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR]), blood pressure, appetite-related hormones from a mixed-meal tolerance test, and continuous glucose levels were also measured. Baseline to 6-week change in TST was greater in the sleep-extension group, at 79 (95% confidence interval [CI] 68.90, 88.05) versus 6 (95% CI -4.43, 16.99) min. Change in the sleep-extension and control groups respectively also showed: lower fasting insulin (-11.03 [95% CI -22.70, 0.65] versus 7.07 [95% CI -4.60, 18.74] pmol/L); lower systolic (-11.09 [95% CI -17.49, -4.69] versus 0.76 [95% CI -5.64, 7.15] mmHg) and diastolic blood pressure (-12.16 [95% CI -17.74, -6.59] versus 1.38 [95% CI -4.19, 6.96] mmHg); lower mean amplitude of glucose excursions (0.34 [95% CI -0.57, -0.12] versus 0.05 [95% CI -0.20, 0.30] mmol/L); lower fasting peptide YY levels (-18.25 [95%CI -41.90, 5.41] versus 21.88 [95% CI -1.78, 45.53] pg/ml), and improved HOMA-IR (-0.51 [95% CI -0.98, -0.03] versus 0.28 [95% CI -0.20, 0.76]). Our protocol increased TST and improved markers of metabolic health in male overweight/obese short sleepers.

Sleep duration and sleep efficiency in UK long-distance heavy goods vehicle drivers

OBJECTIVES

To profile sleep duration and sleep efficiency in UK long-distance heavy goods vehicle (HGV) drivers and explore demographic, occupational and lifestyle predictors of sleep.

METHODS

Cross-sectional analyses were carried out on 329 HGV drivers (98.5% men) recruited across an international logistics company within the midland's region, UK. Sleep duration and efficiency were assessed via wrist-worn accelerometry (GENEActiv) over 8 days. Proportions of drivers with short sleep duration (<6 hour/24 hours and <7 hour/24 hours) and inadequate sleep efficiency (<85%) were calculated. Demographic, occupational and lifestyle data were collected via questionnaires and device-based measures. Logistic regression assessed predictors of short sleep duration and inadequate sleep efficiency.

RESULTS

58% of drivers had a mean sleep duration of <6 hour/24 hours, 91% demonstrated <7-hour sleep/24 hours and 72% achieved <85% sleep efficiency. Sleeping <6 hour/24 hours was less likely in morning (OR 0.45, 95% CI 0.21 to 0.94) and afternoon (OR 0.24, CI 0.10 to 0.60) shift workers (vs night) and if never smoked (vs current smokers) (OR 0.45, CI -0.22 to 0.92). The likelihood of sleeping <7 hour/24 hours reduced with age (OR 0.92, CI 0.87 to 0.98). The likelihood of presenting inadequate sleep efficiency reduced with age (OR 0.96, CI 0.93 to 0.99) and overweight body mass index category (vs obese) (OR 0.47, CI 0.27 to 0.82).

CONCLUSIONS

The high prevalence of short sleep duration and insufficient sleep quality (efficiency) rate suggest that many HGV drivers have increased risk of excessive daytime sleepiness, road traffic accidents and chronic disease. Future sleep research in UK HGV cohorts is warranted given the road safety and public health implications.

323 Is daytime napping a risk factor for persistent insomnia symptoms?

Introduction

Napping, episodes of short daytime sleep separated from the main sleep period, can compensate for the detrimental effects of inadequate night-time sleep or, as ‘siestas’, may form an integral part of personal sleep-wake schedules. Napping may also precipitate or perpetuate insomnia symptoms through the erosion of homeostatic sleep pressure at night. Using longitudinal data, these analyses were designed to evaluate links between daytime napping styles and the incidence of persistent insomnia symptoms, in a sample of middle aged and older adult good sleepers at baseline.

Methods

567 participants (65% female; &gt;35 years old) were sub-sampled from the NITES cohort (Perlis et al, 2019). All were self-rated good sleepers, reporting typical sleep latencies (5 nights/week) and WASO durations of = 1 nap/baseline period) or habitual (&gt;= 2 naps/week). ‘Persistent insomnia symptoms’ cases reported sleep initiation and/or maintenance complaints on &gt;= 3 nights/week for at least two consecutive weeks. Relationships between nap categories and the incidence of persistent insomnia symptoms arising in months 4–12 of the study were assessed in logistic regression models adjusted for age, gender, employment status and depression. Risk is expressed as the odds ratio (OR) with 95% confidence interval (CI).

Results

Prevalence rates for ever/habitual napping were 57% and 10%. Unemployed status and aged 50+ significantly increased habitual nap probability. The 1-year incidence of persistent insomnia symptoms was 5.6%. In logistic regression models, ‘ever’ napping was associated with an almost 3-fold increase in the risk of developing persistent insomnia symptoms (OR=2.994; 95% CI 1.244–6.969; p=.014). When the logistic regression model was rerun with habitual napping, the risk attenuated substantially (OR = 1.4, 95% CI .592–3.163; p=.463).

Conclusion

These results suggest that napping patterns serve as a marker for insomnia symptom development, with haphazard non-habitual napping patterns associated with significantly greater risk.

Support (if any)

RP: Loughborough University doctoral studentship; MP: K24AG055602 & R01AG041783 (NITES).

Sleep Characteristics of Highly Trained Wheelchair Rugby Athletes With and Without a Cervical Spinal Cord Injury During the Competitive Season

Sleep behaviors although significantly relevant to exercise recovery are poorly characterized in Para-sport athletes. Therefore, the main aims of this study were to describe sleep quality and quantity of highly trained wheelchair rugby (WR) athletes during the competitive season, and to investigate whether impairment type or attending a training camp influenced sleep outcomes. Eighteen male WR athletes (mean ± SD; age: 30 ± 5 years) with cervical spinal cord injuries (n = 11) (CSCI) and without (n = 7) (NON-SCI) wore an activity monitor over a 16-day period to objectively quantify sleep parameters, while the Pittsburgh Sleep Quality Index (PSQI) and nightly sleep diary entries were used as subjective means. A sub-sample of the athletes (n = 11) had their sleep monitored during a 3-night training camp to assess the impact of environmental change on sleep. Furthermore, as an additional exploratory measure core temperature was measured for a single night-time period using ingestible telemetry capsules. The athletes had total sleep times and sleep efficiency scores of 7.06 (1.30) h.min [median (interquartile range)] and 81 (9)%, respectively. Sleep onset latency and wake after sleep onset were 13 (24) min and 1.11 (0.45) h.min, respectively. No significant differences were found in objective sleep variables between the impairment groups despite the CSCI group being significantly more likely to report a poorer night's sleep (p = 0.04). Furthermore, attending the training camp caused a significant reduction in total sleep time for both groups [Δ38 ± 33 min; (95% CI: 18–60 min) p < 0.01]. This study highlights suboptimal sleep characteristics that are present in both CSCI and NON-SCI wheelchair athletes, as defined by the National Sleep Foundation. Although objective scores did not differ between groups, athletes with a CSCI rated their sleep worse. Furthermore, the disruption of sleep during training camp reflects an additional risk factor that is important to recognize for those working with wheelchair athletes.

0539 Are Short Sleepers Uncoupled Sleepers?

Introduction

While short sleep durations (&lt;7h/night) are associated with increased diabetes risk, there is limited evidence that increasing the habitual sleep duration of short sleepers is either feasible, or will reliably improve metabolic health outcomes. Furthermore, in the absence of insomnia disorder, it remains unclear whether habitual short sleep mainly reflects a genetic predisposition or a lifestyle choice. In a randomized controlled study we delivered a sleep extension protocol based on CBTi principles to overweight ‘short sleepers’ at increased risk of Type II diabetes.

Methods

18 male short sleepers (Mage=41.4; MBMI=29.57; baseline mean TST=5.8 h/ night) with no complaints of insomnia were randomized to the sleep extension intervention or control condition (printed sleep hygiene advice). The 6-week intervention commenced with personalized sleep re-scheduling negotiated in a 60-minute 1-to-1 session, and supported by elements of sleep hygiene, stimulus control, relaxation and cognitive strategies. Outcomes included sleep duration (actigraphy), fasting insulin, Mean Amplitude of Glycemic Excursions (MAGE) from continuous glucose monitoring, and blood pressure. Data were analyzed in linear fixed effects models including time, group and baselines values.

Results

Adherence to the 6-week protocol was high. Relative to controls (n=8), intervention participants (n = 10) showed a significant increase in TST (95%CI 46.91min, 101.64min, p&lt;0.001; MDiff = 79.4min, p&lt;0.001) and significant reductions in fasting insulin (95%CI -32.08 pmol/L, -.97.0 pmol/L; p=0.04; MDiff = -10.2 pmol/L, p=0.06); MAGE (95%CI -0.77, -0.08, p=0.02; MDiff -0.35, p=0.05) and diastolic (95%CI -22, -5, p=0.004; MDiff=-12, p=0.004); and systolic blood pressure (95%CI -20, -2, p=0.03; MDiff=-10, p=0.006).

Conclusion

CBTi-based sleep extension protocols offer feasible and effective lifestyle interventions in the management of metabolic health in overweight short sleepers who fit published categorization of non-complaining poor sleepers with an undeveloped insomnia identity whose subjective sleep experience and objective sleep characteristics are ‘uncoupled’.

Support

School of Sport, Exercise and Health Sciences, Loughborough University

Psychomotor Performance Decrements following a Successful Physical Activity Intervention for Insomnia

Objectives: Evidence supports the view that reductions in cognitive hyperarousal contribute substantially to improved sleep outcomes following cognitive and behavioral interventions for insomnia disorder. Assuming an inverted-u relationship between arousal and performance, a theoretical possibility, supported by limited empirical data, is that the same mediating processes could negatively impact aspects of psychomotor performance, reducing speed on tests of reaction time. Participants: Sedentary participants (mean age = 59.8; SD = 9.46) meeting research diagnostic criteria for insomnia were randomized to either an exercise intervention of ≥150 min of moderate-intensity activity per week (n = 20), or a wait-list control group (n = 21). Of these, n = 17 intervention and n = 18 control participants completed 6-month follow-up assessments. Methods: Digit span, and simple and complex vigilance task performance was assessed using a computerized protocol at baseline and 6-month follow-up. Dependent variables included digit span, simple reaction time (SRT), complex reaction time (CRT), false positive responses, number of lapses, and SRT/CRT ratio (indicative of the magnitude of difference between simple and complex RT performance). The primary clinical outcome was Insomnia Severity Index (ISI) score. Results: In comparisons of baseline to follow-up change, ISI scores showed clinically significant improvement in the intervention group at 6-month follow-up (F (8,26) = 5.16; P = 0.03). Baseline vigilance performance was equivalent in both groups. At 6-month follow-up, however, the intervention group showed significantly slower simple reaction time F(4,30) = 10.25, p < 0.01, and a significantly decreased SRT/CRT ratio (F(4,30) = 13.22, p < 0.01). Conclusions: Among people meeting diagnostic criteria for insomnia, beneficial sleep outcomes following successful behavioral interventions may, under some circumstances, come at the cost of slower psychomotor performance.

Regular physical activity and insomnia: An international perspective

Both very low and very high levels of regular physical activity have been associated with degraded sleep quality. Cross-national variations in habitual physical activity levels, therefore, may contribute to cross-national differences in insomnia prevalence. The present study assesses and compares the extent to which weekly durations of moderate-intensity physical activity contribute to insomnia risk. Demographic, sleep, physical activity and general health profiles were obtained from a convenience sample of 9,238 adults drawn from five countries (South Africa, Australia, China, South Korea and the UK) using social media. Insomnia prevalence, using DSM-5 criteria, ranged from 4.1% (China) to 14.8% (UK). Evaluating risk using logistic regression adjusted only for age and gender, the lowest level of activity (<10 continuous min per week) was associated with significant insomnia risk (odds ratio = 1.37; 95% confidence interval = 1.05-1.79; p < 0.05). However, when adjusted for all covariates except country, only the highest level of physical activity (>300 min per week) was associated with significantly increased insomnia risk (odds ratio = 1.30; 95% confidence interval = 1.03-2.51; p < 0.05). Risk associated with high activity remained after the addition of "country" to the model (odds ratio = 1.31; 95% confidence interval = 1.02-1.69; p < 0.05). Across all models, female gender, low-rated health, low education and older age consistently increased insomnia risk. These cross-national data indicate that extremes of inactivity/activity can significantly influence insomnia risk independent of country. Insomnia risk associated with very low levels of activity may be mediated by poorer health and disadvantageous social status. However, while very high levels of activity increase insomnia risk independent of health and demographic factors, they may also confound with personally and occupationally demanding lifestyles.