Experimental Study On Sleep And Arousal Regulation In Healthy Young Men In Cross-Circadian Conditions

With improvement in the requirements of the New Military Training Syllabus for actual combat,it has become the focus of training to increase the difficulty,break through limits and improve the all-weather and all-time-domain combat environment capability of personnel.In the complex flight environment and variable meteorological conditions,long-distance,high-intensity and cross-sleep rhythm flight training missions for pilots are becoming more important.Lack of sleep can make pilots less able to function effectively,thus affecting the level of flight training and flight safety.This is especially true when pilots fly day and night time missions across time zones.The quality of necessary sleep is greater,which requires pilots to have good sleep and awakening adjustment abilities.Therefore,it is of great practical significance to study the regulation of sleep and wakefulness across circadian rhythms.At present,drugs regulating biological rhythms are generally used to achieve cross-rhythm sleep at home and abroad,but there are several side effects.It has been reported that prevention of cross-rhythm flight fatigue often involves the use of stimulants,such as modafinil,to maintain arousal levels,but drugs are prone to induce dependence and addiction.Therefore,the aim of the present study was to find safe and reliable,simple,and easy to learn,low cost,easy to promote intervention measures to realize the regulation of trans-rhythmic sleep and post-flight awakening after fatigue.The goal is to help pilots complete trans-rhythmic flight missions safely and efficiently.In order to determine the experimental effect without affecting the training and safety of active pilots,this study selected healthy young male college students as subjects to conduct the following experiments:Part Ⅰ: The influence of music and meditation rapid relaxation training on cross-rhythm sleep Objective: To simulate the cross-rhythm flight task at 2:00 am,and to explore the effect of training on cross-rhythm sleep by shortening the sleep latency period through music and meditation rapid relaxation training.Methods: Based on the Pittsburgh Sleep Scale Index(PSQI),Sleep Belief and Attitude Scale(DBAS)and the Five-factor Mindfulness Scale(FFMQ),90 male subjects with normal sleep quality(PSQI)had scores that ranged from 3 to 7.They all had good sleep beliefs,attitudes,and mindfulness(DBAS,FFMQ)scores > 90 were randomly divided into a meditation group,music group and control group.The music group played music before going to bed and the meditation group played meditation instructions designed to train them to relax quickly and fall asleep.Initially,4 weeks of sleep latency reduction training was conducted and the variation trend index of the frequency of heart rate variability-LF/HF was used to evaluate the change of SL duration.The training effect was evaluated and subsequently 2 weeks of cross-rhythm sleep training was conducted.After training,we retested PSQI,DBAS and FFMQ.Results: Compared with the control group,the SL duration was significantly shortened after rapid relaxation training using music or meditation(P < 0.05);the performance of the meditation group was better than the music group(P < 0.05).After further training,both the music group and the meditation group achieved cross-rhythm sleep(P < 0.05).The PSQI scores of the other two groups were significantly lower after training than before training(P < 0.05),except for the control group.The scores of DBAS and FFMQ in the music group and the meditation group increased significantly after training compared with before training(P < 0.05).Conclusion: The experiments revealed that both music and meditation rapid relaxation training can effectively shorten the sleep incubation period(meditation relaxation training being more effective than music relaxation training),improve the efficiency of falling asleep,and achieve cross-rhythm sleep.Part Ⅱ: Effects of green light on circadian sleep,multitasking performance and alertness levels Objectives: To simulate cross-day and night flight tasks at 4:00 am,and to explore the effects of green light irradiation on the circadian rhythms of subjects on their multi-tasking performances and response ability.Green light irradiation for 30 min before sleep and the whole sleep was examined on the premise of ensuring sufficient and effective sleep time.Methods: According to PSQI,MEQ and MCTQ,40 male subjects with normal sleep quality(PSQI scores ranging from 3 to 7)and no significant difference in sleep time types(MEQ and MCTQ scores were intermediate)were selected,and randomly divided into experimental and control groups.They slept from 21:00 to 4:00 the next day.The experimental group were exposed to green light 30 min before going to bed and throughout the night,while the control group received no interventions.HRV was measured throughout the whole process.Saliva melatonin concentrations were measured before subjects went to bed and after awakening.After waking up,the two groups were tested for their response abilities.Multi-task performance tests and NASA-TLX measurement,through task performance and response ability scores to evaluate the level of arousal and alertness were conducted.Results: After green light irradiation before going to bed and throughout the night,the salivary melatonin concentration of the experimental group was lower than that of the control group(all P < 0.05).LF/HF,SDNN and LFnorm in the experimental group were increased compared to the control group(all P < 0.05),while HFnorm was decreased compared to the controls(P < 0.05).The response ability test and man-machine functional multi-task performances of the experimental group were significantly greater than the control group(all P < 0.05).The total score of NASA-TLX scale in the experimental group had no significant difference compared with that before intervention.Conclusion: Green light exposure 30 min before bedtime and throughout the night can advance circadian rhythm,improve subjects’ arousal and alertness levels,and effectively improve their multitasking performance and responsiveness.Part Ⅲ: Effects of delayed melatonin secretion produced by red light illumination on multitasking performance and alertness Objective: To investigate the effect of delayed melatonin secretion induced by red light irradiation 30 min before bedtime and during the whole sleep on subjects’ multitasking performance and reactivity levels under the premise of ensuring adequate sleep time.Methods: 40 male subjects with normal sleep quality(PSQI scores ranged from 3 to 7)and no significant differences in sleep duration(MEQ and MCTQ scores were intermediate)were selected through after PSQI,MEQ and MCTQ analysis.The subjects were randomly divided into experimental and control groups.The subjects slept at night from 23:00 to 7:00 the next day.The experimental group were exposed to red light for 30 min before going to bed and throughout the night,while the control group received no intervention measures;heart rate variability indicators were measured throughout the experiment.Saliva melatonin concentrations were determined before subjects went to bed and after waking up.After awakening,the two groups were subjected to reaction ability and multi-task performance tests,and NASA-TLX measurement,and the levels of arousal and alertness were evaluated through task performance and reaction ability scores.Results: After red light irradiation before going to bed and throughout the night,salivary melatonin concentrations in the experimental group were higher than in the control group(all P < 0.05).There was no significant difference in the response ability test and man-machine function multi-tasking performance between the experimental and control groups,and no significant differences in the heart rate variability index between the groups.The total score of NASA-TLX scale in the experimental group had no significant difference compared with that before intervention.Conclusion: Red light exposure can delay the secretion of melatonin to some extent,but there was no significant difference between the two groups in multitasking performance and reactivity performance,so the regulation of circadian rhythm needs to be further studied.Part Ⅳ: Effects of physiological electrical stimulation on the arousal level after fatigue during multitasking performance and alertness level tests Objective: To study the effects of physiological electrical stimulation on the arousal and alertness levels of subjects in the simulation of long-duration flight fatigue under sleep deprivation conditions,and to investigate the effects of physiological electrical stimulation on their multitasking performance and responsiveness.Methods: 40 subjects were selected and randomly divided into experimental and control groups.After 8:00 to 8:00 sleep deprivation for 24 h,the next day the following parameters were measured: the heart rate variability index,every 2 h,to measure subjective fatigue,balance and reaction times;at 10 am,multitask performance and NASA-TLX scale were evaluated for the two groups at 10:00-10:30,3:00-3:30,and 4:00-4:30 in the morning,respectively,as were the results of normal state,fatigue state and multi-task performance after stimulation.Electrical stimulation(stimulation level 15,frequency 1.023 Hz,duration 115 ms,power range 0.5 ～ 206MW)was given to the experimental group at 4 am but not to the control group.Results: Subjective fatigue,orthostatic balance,reaction time tests and multi-task performance of the two groups were significantly decreased compared with the normal condition(all P < 0.05).In the two groups,MEANN,RMSSD,SDSD,NN50,p NN50 and HFnorm were higher than normal(All P < 0.05).LFnorm,LF/HF and BMP were lower than normal(all P < 0.05).After electric stimulation,the multi-task performance of the experimental group returned to the normal level(P < 0.01).After2 h,subjective fatigue,vertical balance and reaction time test scores remained relatively high(all P < 0.05).In the experimental group,SDNN,LFnorm,LF/HF and BMP were increased compared to the fatigue state(all P < 0.05),MEANN and HFnorm were decreased compared to the fatigue state(all P < 0.05).There was no statistically significant difference between the scores of the control group and the fatigue group.Conclusion: The sleep deprivation fatigue model can simulate well fatigue after a long flight in the main form of mental fatigue,and physiological electrical stimulation after fatigue can effectively improve the arousal level and alertness level of subjects,improve the performance level of multi-tasking and the level of response ability.SummaryThe present study investigated the effects of music,meditation rapid relaxation training,and light on cross-rhythm sleep,as well as the effects of physiological electrical stimulation on fatigue relief and recovery,and revealed the following results:(1)After 4 weeks of rapid relaxation training guided by music and meditation,both the music and the meditation groups effectively shortened their sleep latency period.The meditation group performed better than the music group in shortening the time.After 2 weeks of cross-rhythm sleep training,both the music and the meditation groups achieved cross-rhythm sleep.(2)Green light effectively advanced the circadian rhythm and restore multitasking performance and responsiveness.(3)Red light delayed the secretion of melatonin to a certain extent,but there was no significant difference in multi-task performance and response ability,so the delayed effect of circadian rhythm needs to be further explored.(4)Physiological electrical stimulation effectively restored arousal and alertness levels after a long time(flight fatigue),and the performance of multi-tasking and response ability was significantly improved compared with that at the time of fatigue.