The Effect of Experimental Recuperative and Appetitive Post-lunch Nap Opportunities, With or Without Caffeine, on Mood and Reaction Time in Highly Trained Athletes

Purpose: To investigate the effects of placebo (PLA), 20 min nap opportunity (N20), 5mg·kg−1 of caffeine (CAF), and their combination (CAF+N20) on sleepiness, mood and reaction-time after partial sleep deprivation (PSD; 04h30 of time in bed; study 1) or after normal sleep night (NSN; 08h30 of time in bed; study 2).Methods: Twenty-three highly trained athletes (study 1; 9 and study 2; 14) performed four test sessions (PLA, CAF, N20 and CAF+N20) in double-blind, counterbalanced and randomized order. Simple (SRT) and two-choice (2CRT) reaction time, subjective sleepiness (ESS) and mood state (POMS) were assessed twice, pre- and post-intervention.Results: SRT was lower (i.e., better performance) during CAF condition after PSD (pre: 336 ± 15 ms vs. post: 312 ± 9 ms; p < 0.001; d = 2.07; Δ% = 7.26) and NSN (pre: 350 ± 39 ms vs. post: 323 ± 32 ms; p < 0.001; d = 0.72; Δ% = 7.71) compared to pre-intervention. N20 decreased 2CRT after PSD (pre: 411 ± 13 ms vs. post: 366 ± 20 ms; p < 0.001; d = 2.89; Δ% = 10.81) and NSN (pre: 418 ± 29 ms vs. post: 375 ± 40 ms; p < 0.001; d = 1.23; Δ% = 10.23). Similarly, 2CRT was shorter during CAF+N20 sessions after PSD (pre: 406 ± 26 ms vs. post: 357 ± 17 ms; p < 0.001; d = 2.17; Δ% = 12.02) and after NSN (pre: 386 ± 33 ms vs. post: 352 ± 30 ms; p < 0.001; d = 1.09; Δ% = 8.68). After PSD, POMS score decreased after CAF (p < 0.001; d = 2.38; Δ% = 66.97) and CAF+N20 (p < 0.001; d = 1.68; Δ% = 46.68). However, after NSN, only N20 reduced POMS (p < 0.001; d = 1.05; Δ% = 78.65) and ESS (p < 0.01; d = 0.71; Δ% = 19.11).Conclusion: After PSD, all interventions reduced sleepiness and only CAF enhanced mood with or without napping. However, only N20 enhanced mood and reduced sleepiness after NSN. Caffeine ingestion enhanced SRT performance regardless of sleep deprivation. N20, with or without caffeine ingestion, enhanced 2CRT independently of sleep deprivation. This suggests a different mode of action of napping and caffeine on sleepiness, mood and reaction time.

Effects of Acute-Partial Sleep Deprivation on High-Intensity Exercise Performance and Cardiac Autonomic Activity in Healthy Adolescents

Performing high-intensity exercise (HIE) in the morning under sleep deprivation may harm the health benefits related to sufficient sleep and HIE. Therefore, the aim of this study was to explore the effects of acute-partial sleep deprivation on HIE performance and cardiac autonomic activity by monitoring heart rate variability (HRV) indices. Twenty-nine healthy male adolescents in college were recruited to perform a one-time HIE session on the treadmill (Bruce protocol) after ≥7 h of normal control sleep (control) and after ≤4 h of acute-partial sleep deprivation (SD). At the beginning of control and SD periods and after exercising under the two sleep conditions, heart rate (HR), standard deviation of normal to normal (SDNN), square root of the mean squared differences of successive NN intervals (RMSSD), normalized low frequency power (LFn), normalized high frequency power (HFn), number of pairs adjacent NN intervals differing by ≥50 ms in the entire recording count divided by the total number of all NN intervals (pNN50), and short axis and long axis value in Poincaré plot (SD1 and SD2) were measured at rest in an upright sitting position. The participants slept 7.63 ± 0.52 and 3.78 ± 0.69 h during control and SD periods, respectively (p < 0.001). Compared with the control participants, those suffering sleep deprivation experienced a significant decrease in exercise duration, RMSSD, HFn, SD1, and pNN50 as well as a significant increase in maximum heart rate during exercise (p < 0.05). SDNN, RMSSD, HFn, SD1, and pNN50 decreased significantly after exercise (p < 0.05 and 0.01 and 0.001, respectively). In summary, acute-partial sleep deprivation affected aerobic exercise performance the next morning and led to decreased cardiac vagus activity and cardiac autonomic dysfunction.

Confinement, partial sleep deprivation and defined physical activity–influence on cardiorespiratory regulation and capacity

Introduction Adequate cardiorespiratory fitness is of utmost importance during spaceflight and should be assessable via moderate work rate intensities, e.g., using kinetics parameters. The combination of restricted sleep, and defined physical exercise during a 45-day simulated space mission is expected to slow heart rate (HR) kinetics without changes in oxygen uptake ($${\dot{\text{V}}\text{O}}_{{2}}$$ V ˙ O 2 ) kinetics. Methods Overall, 14 crew members (9 males, 5 females, 37 ± 7 yrs, 23.4 ± 3.5 kg m−2) simulated a 45-d-mission to an asteroid. During the mission, the sleep schedule included 5 nights of 5 h and 2 nights of 8 h sleep. The crew members were tested on a cycle ergometer, using pseudo-random binary sequences, changing between 30 and 80 W on day 8 before (MD-8), day 22 (MD22) and 42 (MD42) after the beginning and day 4 (MD + 4) following the end of the mission. Kinetics information was assessed using the maxima of cross-correlation functions (CCFmax). Higher CCFmax indicates faster responses. Results CCFmax(HR) was significantly (p = 0.008) slower at MD-8 (0.30 ± 0.06) compared with MD22 (0.36 ± 0.06), MD42 (0.38 ± 0.06) and MD + 4 (0.35 ± 0.06). Mean HR values during the different work rate steps were higher at MD-8 and MD + 4 compared to MD22 and MD42 (p < 0.001). Discussion The physical training during the mission accelerated HR kinetics, but had no impact on mean HR values post mission. Thus, HR kinetics seem to be sensitive to changes in cardiorespiratory fitness and may be a valuable parameter to monitor fitness. Kinetics and capacities adapt independently in response to confinement in combination with defined physical activity and sleep.

Sleep Deprivation Deteriorates Heart Rate Variability and Photoplethysmography

IntroductionSleep deprivation has deleterious effects on cardiovascular health. Using wearable health trackers, non-invasive physiological signals, such as heart rate variability (HRV), photoplethysmography (PPG), and baroreflex sensitivity (BRS) can be analyzed for detection of the effects of partial sleep deprivation on cardiovascular responses.MethodsFifteen participants underwent 1 week of baseline recording (BSL, usual day activity and sleep) followed by 3 days with 3 h of sleep per night (SDP), followed by 1 week of recovery with sleep ad lib (RCV). HRV was recorded using an orthostatic test every morning [root mean square of the successive differences (RMSSD), power in the low-frequency (LF) and high-frequency (HF) bands, and normalized power nLF and nHF were computed]; PPG and polysomnography (PSG) were recorded overnight. Continuous blood pressure and psychomotor vigilance task were also recorded. A questionnaire of subjective fatigue, sleepiness, and mood states was filled regularly.ResultsRMSSD and HF decreased while nLF increased during SDP, indicating a decrease in parasympathetic activity and a potential increase in sympathetic activity. PPG parameters indicated a decrease in amplitude and duration of the waveforms of the systolic and diastolic periods, which is compatible with increases in sympathetic activity and vascular tone. PSG showed a rebound of sleep duration, efficiency, and deep sleep in RCV compared to BSL. BRS remained unchanged while vigilance decreased during SDP. Questionnaires showed an increased subjective fatigue and sleepiness during SDP.ConclusionHRV and PPG are two markers easily measured with wearable devices and modified by partial sleep deprivation, contradictory to BRS. Both markers showed a decrease in parasympathetic activity, known as detrimental to cardiovascular health.

High-Intensity Interval Exercise Performance and Short-Term Metabolic Responses to Overnight-Fasted Acute-Partial Sleep Deprivation

People practicing high-intensity interval exercise (HIIE) fasted during the morning hours under a lack of sleep. Such a habit may jeopardize the health benefits related to HIIE and adequate sleep. Fifteen habitually good sleeper males (age 31.1 ± 5.3 SD year) completed on a treadmill two isocaloric (500 kcal) HIIE sessions (3:2 min work:rest) averaged at 70% VO2reserve after 9–9.5 h of reference sleep exercise (RSE) and after 3–3.5 h of acute-partial sleep deprivation exercise (SSE). Diet and sleep patterns were controlled both 1 week prior and 2 days leading up to RSE and SSE. HIIE related performance and substrate utilization data were obtained from the continuous analysis of respiratory gases. Data were analyzed using repeated measures ANOVA with the baseline maximum oxygen uptake (VO2max) and body fat percentage (BF%) as covariates at p < 0.05. No difference was observed in VO2max, time to complete the HIIE, VE, RER, CHO%, and FAT% utilization during the experimental conditions. Whether attaining an adequate amount of sleep or not, the fasted HIIE performance and metabolism were not affected. We propose to practice the fasted HIIE under adequate sleep to receive the pleiotropic beneficial effects of sleep to the human body.

EFFECT OF DIFFERENT TYPES OF SLEEP DEPRIVATION AND SLEEP RECOVERY ON SALIVARY PH

Background: Salivary pH can rise or fall influenced by intrinsic and extrinsic factors. Sleep deprivation is one example of intrinsic factors. Sleep deprivation causes a reduction in sleep time at a certain time. Purpose: Analyze the effect of different types of sleep deprivations and sleep recovery on salivary pH. Method: This study was experimental research with a post-test only with a control group design. Thirty white Wistar strain rats were randomly divided into 5 groups: healthy control group (KI), partial sleep deprivation (PSD/KII), total sleep deprivation (TSD/KIII), partial sleep deprivation, and continued sleep recovery (PSD+SR/KIV) and total sleep deprivation and continued sleep recovery (TSD+SR/KV). The treatment is carried out on a single platform method. Salivary pH was measured with the help of color-coded pH strips that were given grading after the completion of sleep deprivation induction. Result: The mean decrease in salivary pH was highest in the TSD group. One Way ANOVA test showed significant differences (p <0.05) in the control group with PSD and TSD, the PSD group with PSD+SR, TSD group with PSD+SR and TSD+SR. Conclusion: Sleep deprivation is proven to reduce the pH of Saliva. Total sleep deprivation is a chronic condition that has the most influence on decreasing salivary pH. The effect of decreasing salivary pH due to sleep deprivation is proven to be overcome by sleep recovery.