Can adding personalized rule-based feedback improve the therapeutic effect of self-help digital cognitive behavioral therapy for insomnia in young adults?

INTRODUCTION: Cognitive-behavioral therapy for insomnia (CBT-I) is recommended as the first-line treatment for insomnia, but low accessibility and relatively high cost limits the dissemination of the treatment. Several forms of digital CBT-I have been developed to increase the accessibility and shown to be effective; however, the treatment effect may be restricted by the lack of interaction within the treatment. The current study examines whether the therapeutic effects of self-help digital CBT-I could be enhanced by adding simple rule-based personalized feedback. METHOD: Ninety-two young adults with self-reported insomnia were randomly assigned to three groups: a self-help group (SH, n = 31), who received an eight-session email-delivered CBT-I program; a feedback group (FB, n = 31), who went through the same CBT-I program with personalized feedback; and a waitlist group (WL, n = 30). The Insomnia Severity Index (ISI) was used as the primary outcome measure, and the 16-item version of the Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS-16), Sleep Hygiene Practice Scale (SHPS), and sleep diary were used as the secondary outcome measures. Treatment satisfaction and adherence were also compared between the treatment groups. RESULTS: Both the SH and FB groups showed significantly more improvements in insomnia severity, sleep-related beliefs, and sleep hygiene behaviors than the WL group. Sleep onset latency and sleep efficiency in the sleep diary were also significantly improved after treatment. None of these effects significantly differed between the two treatment groups. Nonetheless, participants in the FB group reported higher treatment satisfaction than those in the SH group. CONCLUSION: This study supports the effectiveness of email-delivered self-help CBT-I for young adults with insomnia. Furthermore, while adding simple personalized feedback may not have an additional effect on sleep per se, it can enhance treatment satisfaction. This simple intervention shows promise in addressing sleep disturbance in young adults.

Continuous Positive Airway Pressure Reduces Plasma Neurochemical Levels in Patients with OSA: A Pilot Study.

Obstructive sleep apnea (OSA) is a risk factor for neurodegenerative diseases. This study determined whether continuous positive airway pressure (CPAP), which can alleviate OSA symptoms, can reduce neurochemical biomarker levels. Thirty patients with OSA and normal cognitive function were recruited and divided into the control (n = 10) and CPAP (n = 20) groups. Next, we examined their in-lab sleep data (polysomnography and CPAP titration), sleep-related questionnaire outcomes, and neurochemical biomarker levels at baseline and the 3-month follow-up. The paired t-test and Wilcoxon signed-rank test were used to examine changes. Analysis of covariance (ANCOVA) was performed to increase the robustness of outcomes. The Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index scores were significantly decreased in the CPAP group. The mean levels of total tau (T-Tau), amyloid-beta-42 (Aß42), and the product of the two (Aß42 × T-Tau) increased considerably in the control group (ΔT-Tau: 2.31 pg/mL; ΔAß42: 0.58 pg/mL; ΔAß42 × T-Tau: 48.73 pg2/mL2), whereas the mean levels of T-Tau and the product of T-Tau and Aß42 decreased considerably in the CPAP group (ΔT-Tau: -2.22 pg/mL; ΔAß42 × T-Tau: -44.35 pg2/mL2). The results of ANCOVA with adjustment for age, sex, body mass index, baseline measurements, and apnea-hypopnea index demonstrated significant differences in neurochemical biomarker levels between the CPAP and control groups. The findings indicate that CPAP may reduce neurochemical biomarker levels by alleviating OSA symptoms.

Predictors of dropout in university students participating in an 8-week e-mail-based cognitive-behavioral therapy for insomnia intervention.

PURPOSE: We conducted an exploratory study to identify risk factors of dropout in an 8-week e-mail-based cognitive-behavioral therapy for insomnia (REFRESH) to improve sleep among university students with insomnia symptoms. METHODS: University and graduate students in Hong Kong and Korea who scored higher than 10 on the Insomnia Severity Index participated in REFRESH. RESULTS: Of 158 participants from Hong Kong (n = 43) and Korea (n = 115), 90 (57%) did not complete all 7 sessions, while 52 of 90 (57.8%) dropped out prior to the fourth session. ROC analysis was conducted on the entire sample of 158 participants with intervention completion vs. dropout (non-completion) as the outcome variable. Predictors of dropout were wake time after sleep onset (WASO) < 7.1 min on the weekly sleep diary and expectations for sleep (a subscale of dysfunctional beliefs and attitudes about sleep; DBAS) < 18 at baseline. CONCLUSIONS: These findings indicate that shorter WASO and less expectations for sleep at baseline were associated with risk of dropout from e-mail delivered self-help CBT-I-based intervention. Our results highlight the importance of identifying and tailoring treatment formats to students based on their presenting sleep characteristics.

Associations between risk of Alzheimer's disease and obstructive sleep apnea, intermittent hypoxia, and arousal responses: A pilot study.

Objectives: Obstructive sleep apnea (OSA) may increase the risk of Alzheimer's disease (AD). However, potential associations among sleep-disordered breathing, hypoxia, and OSA-induced arousal responses should be investigated. This study determined differences in sleep parameters and investigated the relationship between such parameters and the risk of AD. Methods: Patients with suspected OSA were recruited and underwent in-lab polysomnography (PSG). Subsequently, blood samples were collected from participants. Patients' plasma levels of total tau (T-Tau) and amyloid beta-peptide 42 (Aß42) were measured using an ultrasensitive immunomagnetic reduction assay. Next, the participants were categorized into low- and high-risk groups on the basis of the computed product (Aß42 × T-Tau, the cutoff for AD risk). PSG parameters were analyzed and compared. Results: We included 36 patients in this study, of whom 18 and 18 were assigned to the low- and high-risk groups, respectively. The average apnea-hypopnea index (AHI), apnea, hypopnea index [during rapid eye movement (REM) and non-REM (NREM) sleep], and oxygen desaturation index (≥3%, ODI-3%) values of the high-risk group were significantly higher than those of the low-risk group. Similarly, the mean arousal index and respiratory arousal index (R-ArI) of the high-risk group were significantly higher than those of the low-risk group. Sleep-disordered breathing indices, oxygen desaturation, and arousal responses were significantly associated with an increased risk of AD. Positive associations were observed among the AHI, ODI-3%, R-ArI, and computed product. Conclusions: Recurrent sleep-disordered breathing, intermittent hypoxia, and arousal responses, including those occurring during the NREM stage, were associated with AD risk. However, a longitudinal study should be conducted to investigate the causal relationships among these factors.

Do alexithymia and negative affect predict poor sleep quality? The moderating role of interoceptive sensibility.

OBJECTIVES: Emotion-related hyperarousal is an important core pathology of poor sleep. Studies investigating the interplay of alexithymia and affective experiences in determining sleep quality have yielded mixed results. To disentangle the inconsistency, this study examined the concurrent predictive power of alexithymia, and negative and positive affect, while incorporating interoceptive sensibility (IS) as a possible moderator. METHODS: A sample of 224 (70.10% were female) participants completed the Toronto Alexithymia Scale, Positive and Negative Affect Schedule, Pittsburgh Sleep Quality Index, Multidimensional Assessment of Interoceptive Awareness (MAIA), and Marlowe-Crowne Social Desirability Scale (for controlling response bias) using paper and pencil. A two-stage cluster analysis of the MAIA was used to capture IS characteristics. Stepwise regression was conducted separately for each IS cluster. RESULTS: A three-group structure for IS characteristics was found. Higher alexithymia was predictive of poor sleep quality in the low IS group, while higher negative affect predicted poor sleep quality in the moderate and high IS groups. Additionally, alexithymia and positive affect were significantly different in the three IS groups, while negative affect and sleep quality were not. CONCLUSIONS: Emotion and cognitive arousal may impact sleep quality differently in individuals with different levels of internal focusing ability, depending on physiological versus emotional self-conceptualization. The implications on pathological research, clinical intervention, study limitations and future directions are discussed.

Predicting Hypnotic Use among Insomnia Patients with the Theory of Planned Behavior and Craving.

While long-term hypnotic use is very common in clinical practice, the associated factors have been understudied. This study aims to explore the cognitive factors that might influence the long-term use of hypnotics based on the theory of planned behavior (TPB), and examines the moderating effect of craving between cognitive intention and actual hypnotic-use behavior at follow-up. A total of 139 insomnia patients completed a self-constructed TPB questionnaire to measure their attitude, subjective norm, perceived behavioral control, and behavioral intention of hypnotic use, as well as the Hypnotic-Use Urge Scale (HUS) to measure their craving for hypnotics. They were then contacted through phone approximately three months later to assess their hypnotic use. Hierarchical regression showed that perceived behavioral control was the most significant determinant for behavioral intention of hypnotic use. Behavioral intention, in turn, can predict the frequency of hypnotic use after three months. However, this association was moderated by hypnotic craving. The association was lower among the participants with higher cravings for hypnotic use. The findings suggest that the patients' beliefs about their control over sleep and daily life situations, and their craving for hypnotics should be taken into consideration in the management of hypnotic use.

How Does E-mail-Delivered Cognitive Behavioral Therapy Work for Young Adults (18-28 Years) with Insomnia? Mediators of Changes in Insomnia, Depression, Anxiety, and Stress.

This study examined whether cognitive behavioral therapy (CBT) for insomnia (CBT-I) improved insomnia severity, by changing sleep-related mediating factors. It also examined whether an improvement in insomnia led to enhanced mental health. This study was a secondary analysis of a randomized controlled trial of e-mail-delivered CBT-I for young adults with insomnia. The participants were randomized to either CBT-I or self-monitoring. The mental health-related measures were depression, anxiety, and stress. The sleep-related mediating factors were sleep hygiene practices, dysfunctional beliefs, sleep reactivity, and pre-sleep arousal. A total of 41 participants, who completed all the sessions (71% females; mean age 19.71 ± 1.98 years), were included in the analysis. The hierarchical multiple regression analysis showed that 53% of the variance in the improvements in insomnia severity was explained by the treatment group (ß = −0.53; ΔR2 = 0.25; p < 0.01) and the changes in sleep reactivity (ß = 0.39; ΔR2 = 0.28; p < 0.05). Moreover, the mediation analysis showed that the reductions in depression and stress were explained by the changes in insomnia severity; however, anxiety symptoms were not reduced. CBT-I for young adults suggested that sleep reactivity is a significant mediator that reduces insomnia severity, and that the alleviation and prevention of depression and stress would occur with the improvement in insomnia.

Lower activity linkage between caregivers and persons with neurodegenerative diseases is associated with greater caregiver anxiety.

Physiological linkage refers to the degree to which two individuals' central/peripheral physiological activities change in coordinated ways. Previous research has focused primarily on linkage in the autonomic nervous system in laboratory settings, particularly examining how linkage is associated with social behavior and relationship quality. In this study, we examined how linkage in couples' daily somatic activity (e.g., synchronized movement measured from wrist sensors)-another important aspect of peripheral physiology-was associated with relationship quality and mental health. We focused on persons with neurodegenerative diseases (PWNDs) and their spousal caregivers, whose linkage might have direct implications for the PWND-caregiver relationship and caregiver's health. Twenty-two PWNDs and their caregivers wore wristwatch actigraphy devices that provided continuous measurement of activity over 7 days at home. PWND-caregiver activity linkage was quantified by the degree to which activity was "in-phase" or "anti-phase" linked (i.e., coordinated changes in the same or opposite direction) during waking hours, computed by correlating minute-by-minute activity levels averaged using a 10-min rolling window. Caregivers completed well-validated surveys that assessed their mental health (including anxiety and depression) and relationship quality with the PWND. We found that lower in-phase activity linkage, but not anti-phase linkage, was associated with higher caregiver anxiety. These dyad-level effects were robust, remaining significant after adjusting for somatic activity at the individual level. No effects were found for caregiver depression or relationship quality. These findings suggest activity linkage and wearables may be useful for day-by-day monitoring of vulnerable populations such as family caregivers. We offered several possible explanations for our findings.

Efficacy of Email-delivered Versus Face-to-face Group Cognitive Behavioral Therapy for Insomnia in Youths: A Randomized Controlled Trial.

PURPOSE: The purpose of the study was to compare the efficacy of group-based therapy (GT) and email-delivered self-help (ESH) cognitive behavioral therapy for insomnia (CBT-I) with the wait-list (WL) control group in youths. METHODS: The study involved an assessor-blind, parallel group randomized controlled trial in youths meeting the diagnostic criteria for insomnia disorder. Participants were randomized to one of the three groups (8-week GT, 8-week ESH, or WL). Participants in all three groups were assessed at baseline and after treatment (week 9 for the WL group). The two treatment groups were additionally assessed at one month and six months after the intervention. Treatment effects were examined using linear mixed models. RESULTS: A total of 135 youths (mean age: 20.0 ± 2.5 years, female: 67.4%) were recruited. After treatment, both active treatment groups showed significant improvements in insomnia symptoms (GT vs. WL: Cohen's d = -1.03, ESH vs. WL: d = -.63), less presleep arousal (d = -.52 to -1.47), less sleep-related dysfunctional belief (d = -.88 to -1.78), better sleep hygiene practice (d = -.79 to -.84), and improved daytime functioning (d = -.56 to -.96) compared with the WL group. In addition, GT outperformed ESH in improving maladaptive sleep-related beliefs and mood symptoms at post-treatment and 6-month follow-up. A reduction of suicidality with moderate effect size favoring GT emerged at 6-month follow-up. DISCUSSION: Our findings suggested that both group-based and email-delivered CBT-I were effective in treating youth insomnia, but group-based CBT-I showed superior effects on reducing maladaptive beliefs and mood symptoms.

Comparative efficacy of digital cognitive behavioral therapy for insomnia: A systematic review and network meta-analysis.

The comparative efficacy of various approaches of digital cognitive behavioral therapy for insomnia (CBTi) is still unclear. This network meta-analysis explored the comparative efficacy of digital CBTi approaches in adults with insomnia. Four electronic databases were searched from inception to June 27, 2020. Primary outcomes were self-reported total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), sleep efficiency (SE), and insomnia symptoms; these were measured using sleep diaries or valid questionnaires. A random-effects network meta-analysis in a frequentist framework was used. Fifty-four randomized controlled trials comprising 11,815 participants were included. Compared with usual care, web-based CBTi with a therapist demonstrated significantly longer TST (mean difference [MD]: 23.19 min, 95% confidence interval [CI]: 18.98-27.39 min), shorter SOL (MD: -18.76 min, 95% CI -24.20 to -13.31 min), lower WASO (MD: -31.40 min, 95% CI: -36.26 to -26.55 min), and greater SE (MD: 10.37%, 95% CI: 8.08%-12.65%). The surface under the cumulative ranking curve indicates that web-based CBTi with therapists is most likely to be ranked the highest among all treatments, and thus, this network meta-analysis suggests that such a treatment is the optimal intervention for improving sleep duration and SE as well as the reductions in SOL and WASO. PROSPERO REGISTRATION NUMBER: CRD42020171134.

Temporal Dynamics of Subjective and Objective Alertness During Exposure to Bright Light in the Afternoon for 5 h.

Light can induce an alertness response in humans. The effects of exposure to bright light vs. dim light on the levels of alertness during the day, especially in the afternoon, as reported in the literature, are inconsistent. This study employed a multiple measurement strategy to explore the temporal variations in the effects of exposure to bright light vs. regular office light (1,200 lx vs. 200 lx at eye level, 6,500 K) on the alertness of participants for 5 h in the afternoon. In this study, 20 healthy adults (11 female; mean age 23.25 ± 2.3 years) underwent the Karolinska sleepiness scale (KSS), the auditory psychomotor vigilance test (PVT), and the waking electroencephalogram (EEG) test for two levels of light intervention. The results yielded a relatively lower relative delta power and a relatively higher beta power for the 1,200 lx condition in comparison with the 200 lx condition. However, the light conditions elicited no statistically significant differences in the KSS scores and performance with respect to the PVT. The results suggested that exposure to bright light for 5 h in the afternoon could enhance physiological arousal while exerting insignificant effects on subjective feelings and performance abilities relating to the alertness of the participants.

Validation of the Japanese version of the Sleep Hygiene Practice Scale.

OBJECTIVE: This study sought to validate the Japanese version of the Sleep Hygiene Practices Scale (SHPS-J). PATIENTS/METHODS: A cross-sectional questionnaire-based study was conducted via the internet. In total, 854 participants (435 men, 419 women; mean age, 42.91 ± 11.54 years) were asked to complete all scales, and 283 of them were asked to complete the same scales two weeks later. The survey consisted of the SHPS-J, the Japanese version of the Insomnia Severity Index (ISI-J), and the Japanese version of the Pittsburgh Sleep Quality Index (PSQI-J). The SHPS-J was developed according to the International Society for Pharmacoeconomics and Outcomes Research Task Force for Translation and Cultural Adaption. For the analysis, participants were divided into three groups: insomnia syndrome, insomnia symptoms, and good sleep groups. RESULTS: The SHPS-J had good test-retest reliability (ICC: 0.55-0.76) and adequate internal consistency (α = 0.54-0.74), except with regard to eating/drinking behaviors. The factorial validity of the four-factor structure was confirmed through a confirmatory factor analysis; however, one item related to eating/drinking behaviors had no significant factor loading. The construct validity was confirmed through a correlation analysis between each domain of the SHPS-J and ISI-J (r = 0.19-0.60, p < 0.01). The results of clinical validation confirmed that all domains of the SHPS-J were significantly higher for individuals with insomnia than for good sleepers. CONCLUSIONS: This study confirmed both the reliability and validity of the SHPS-J.

Can an E-Mail-Delivered CBT for Insomnia Validated in the West Be Effective in the East? A Randomized Controlled Trial.

This study examined the effects of an e-mail-delivered cognitive behavioral therapy for insomnia (CBT-I), validated in Western countries, on insomnia severity, anxiety, and depression in young adults with insomnia in Eastern countries, particularly Japan. This prospective parallel-group randomized clinical trial included college students with Insomnia Severity Index (ISI) scores of ten or higher. Participants were recruited via advertising on a university campus and randomized to an e-mail-delivered CBT-I (REFRESH) or self-monitoring (SM) with sleep diaries group. The primary outcomes were insomnia severity, anxiety, and depression; secondary outcomes were sleep hygiene practices, dysfunctional beliefs, sleep reactivity, and pre-sleep arousal. All measurements were assessed before and after the intervention. A total of 48 participants (mean (SD) age, 19.56 (1.86) years; 67% female) were randomized and included in the analysis. The results of the intent-to-treat analysis showed a significant interaction effect for insomnia severity, anxiety, depression, sleep hygiene practice, and pre-sleep arousal. Compared with the SM group, the REFRESH group was more effective in reducing insomnia severity (Hedges' g = 1.50), anxiety (g = 0.97), and depression (g = 0.61) post-intervention. These findings suggest that an e-mail-delivered CBT-I may be an effective treatment for young adults with elevated insomnia symptoms living in Japan.

An exploration of the sleep quality and potential violence among patients with schizophrenia in community.

PURPOSE: Sleep quality in patients with schizophrenia is correlated with potential violence. However, few studies have conducted in-depth discussions on community patients with schizophrenia. The purpose of this study was to explore the influences of demographic characteristics, psychiatric symptom severity, and sleep quality in community patients with schizophrenia on the risks of potential violence and its subdimensions (ie, physical aggression, verbal aggression, anger, and hostility). DESIGN AND METHODS: This study adopted a cross-sectional research design. Using convenience sampling, 78 community patients with schizophrenia were recruited from psychiatric outpatient clinics, day wards, and those who received home-care services. FINDINGS: This study discovered that sleep quality is a crucial factor that influences the risks of potential violence. Analysis on the subdimensions revealed that having a violence history during the preceding month and sleep quality are crucial factors that influence physical aggression. In addition, sleep quality is a crucial factor that influences the occurrence of anger. Age and sleep quality substantially influence hostility. However, this study did not identify any crucial factors that influenced verbal aggression. PRACTICE IMPLICATIONS: In the future, community nursing professionals should collect data on the patients' age, whether the patients exhibited violence behavior during the preceding month, and their sleep quality to prevent risks of potential violence, physical aggression, anger, or hostility.

Consequences of ignoring the response-shift and measure non-invariant items in sleep studies: an empirical data based simulation of the treatment effect of CBT-I on dysfunctional sleep beliefs.

INTRODUCTION: Previous studies have shown that psychological interventions do not only improve patients' mental symptoms (i.e., true change) but may also change the internal standards patients use to evaluate their symptoms (i.e., response shifts). Although the response shifts could reflect patients' cognitive changes toward their disorders as the interventions aim to achieve, failing to differentiate them from the true change during data analyses could bias the research conclusions. Considering this issue is seldom discussed in sleep studies, this study thus examined the impacts of response-shift items in an intervention study of cognitive behavioral therapy for insomnia (CBT-I) via empirical-data based simulations. METHOD: We used longitudinal measurement invariance tests to identify the items in an abbreviated version of the Dysfunctional Beliefs and Attitudes about Sleep Scale that are non-invariant (response shifted) against CBT-I based on data from 114 insomnia patients. The partial invariance model built accordingly was then used as a population model for simulations to examine the impacts of the response-shift items on follow-up paired t-tests. RESULTS: Invariance tests indicate CBT-I would lift the intercept of one item in DBAS-10 and cause non-uniform calibrations in three items. The following up simulations showed that failing to exclude the intercept-lifted item from the calculations of the subscale scores would lower the probability of using paired t-test to correctly detect the treatment effect by up to 53%. CONCLUSIONS: We recommend sleep researchers to consider the issues of response-shift when assessing sleep-related constructs in interventional studies for insomnia.

Attentional Bias Assessed With Event-Related Potentials in Long-term Hypnotic Users.

PURPOSE/BACKGROUND: Attentional bias toward drug-related cues is considered to be an indication of neurocognitive processes associated with drug dependence. While this phenomenon has been shown in other addictive substances, whether hypnotic medication would lead to similar processes remains an issue to be investigated. The present study examined attentional bias toward drug-related cues in long-term hypnotic users and the effect of negative affect on this process. METHODS/PROCEDURES: Thirteen long-term hypnotic users participated in this study. They spent 2 nights in the sleep laboratory: a mood-induction night and a neutral night. Attentional bias was measured through the recording of event-related potentials using a cue-reactivity paradigm; subjective craving for hypnotics was assessed using a single-item rating scale, and negative affect was measured using the Positive and Negative Affect Schedule. FINDINGS/RESULTS: The results showed that the amplitudes of P300 and slow positive wave for hypnotic-related and sleep-related photographs were significantly higher than those for neutral photographs in both conditions. Negative mood induction did not significantly increase attentional bias. IMPLICATIONS/CONCLUSIONS: The findings provide preliminary evidence that long-term hypnotic users do have attentional bias for hypnotic-related photos, suggesting the possibility of neurocognitive processes associated with drug dependence. However, the results did not show higher attentional bias under negative mood, suggesting that the use of hypnotics is not reinforced by the desire to eliminate negative affect. Because of the limited sample size and lack of a control group, the results should be considered as preliminary findings that call for future studies to further investigate this issue.

Relationship between heart rate variability and aggressive behavior among patients with schizophrenia hospitalized in acute wards.

PURPOSE: To explore the state of mental treatment, heart rate variability (HRV), level of aggressive behavior, and their relationships among hospitalized patients with schizophrenia. DESIGN AND METHODS: This study adopted a follow-up design and convenience sampling. Thirty-three subjects completed the questionnaire, and their HRV indices were measured. FINDINGS: Patients' psychiatric symptoms showed a significant downward trend after hospitalization (P = .003). The standard deviation of the normal-to-normal intervals in the morning was significantly correlated with overall aggression, physical aggression, and verbal aggression. PRACTICE IMPLICATIONS: HRV can be regularly monitored among inpatients with schizophrenia with a risk of high aggression as an indicator of possible aggressive behavior.

Long Hours' Effects on Work-Life Balance and Satisfaction.

PURPOSE: In this study, we examined whether the associations between working hours, job satisfaction, and work-life balance are mediated by occupational stress. In addition, we tested whether perceived time control helps moderate the effects of working hours and occupational stress. METHODOLOGY: Questionnaires were administered to 369 respondents working in the high-tech and banking industries. Analyses were then conducted on the data. FINDINGS: The analysis revealed significant correlations between long working hours and both occupational stress and work-life balance, as well as between occupational stress and both work-life balance and job satisfaction. In addition, the relationship between working hours and occupational stress exhibited a significantly positive interaction with perceived time control. VALUE: The results indicate the importance of giving workers greater control over working hours. We therefore recommend that labor laws should be revised as necessary to prevent excessive working hours and enhance work-time flexibility.

The Acute Effects of Intermittent Light Exposure in the Evening on Alertness and Subsequent Sleep Architecture.

Exposure to bright light is typically intermittent in our daily life. However, the acute effects of intermittent light on alertness and sleep have seldom been explored. To investigate this issue, we employed within-subject design and compared the effects of three light conditions: intermittent bright light (30-min pulse of blue-enriched bright light (~1000 lux, ~6000 K) alternating with 30-min dim normal light (~5 lux, ~3600 K) three times); continuous bright light; and continuous dim light on subjective and objective alertness and subsequent sleep structure. Each light exposure was conducted during the three hours before bedtime. Fifteen healthy volunteers (20 ± 3.4 years; seven males) were scheduled to stay in the sleep laboratory for four separated nights (one for adaptation and the others for the light exposures) with a period of at least one week between nights. The results showed that when compared with dim light, both intermittent light and continuous bright light significantly increased subjective alertness and decreased sleep efficiency (SE) and total sleep time (TST). Intermittent light significantly increased objective alertness than dim light did during the second half of the light-exposure period. Our results suggested that intermittent light was as effective as continuous bright light in their acute effects in enhancing subjective and objective alertness and in negatively impacting subsequent sleep.

The neurophysiological basis of the discrepancy between objective and subjective sleep during the sleep onset period: an EEG-fMRI study.

Subjective perception of sleep is not necessarily consistent with electroencephalography (EEG) indications of sleep. The mismatch between subjective reports and objective measures is often referred to as "sleep state misperception." Previous studies evince that this mismatch is found in both patients with insomnia and in normal sleepers, but the neurophysiological mechanism remains unclear. The aim of the study is to explore the neurophysiological basis of this mechanism, from the perspective of both EEG power and functional magnetic resonance imaging (fMRI) fluctuations. Thirty-six healthy young adults participated in the study. Simultaneous EEG and fMRI recordings were conducted while the participants were trying to fall asleep in an MRI scanner at approximately 9:00 pm. They were awakened after achieving stable N1 or N2 sleep, or after 90 min without falling into stable sleep. Next they were asked to recall their conscious experiences from the moment immediately prior to awakening. Sixty-one instances of scheduled awakenings were collected: 21 of these after having achieved stable stage N2 sleep; 12, during stage N1 sleep; and, 20 during the waking state. Relative to those awakenings without subjective-objective discrepancy (n = 27), these awakenings with discrepancy (n = 14) were associated with lower θ power, as well as higher α, ß, and γ power. Moreover, we found that participants who exhibited the discrepancy, compared with those who did not, evinced a higher amplitude of low-frequency fluctuation levels in the prefrontal cortex. These results lend support to the conjecture that the subjective-objective discrepancy is associated with central nervous system hyperarousal.