A clinical approach to circadian rhythm sleep disorders

Study of insomnia in rotating shift-workers

BACKGROUND

Shift-workers commonly suffer from insomnia. This study evaluates different domains of insomnia.

AIM

This study was aimed to study sleep and insomnia in rotating shift-workers and compare with day-workers.

MATERIALS AND METHODS

This was case-control study. The sleep of rotating shift-workers is compared with day workers using Athens Insomnia Scale.

RESULTS

Rotating shift-workers had significantly higher scores on Athens insomnia scale on domains of initial, intermediate and terminal insomnia than day workers. Duration and quality of sleep and sense of well-being are lower in rotating shift-workers. Rotating shift-workers also experienced more day-time sleepiness than day workers. However, there was no difference in perceived physical and mental functioning between the two groups.

CONCLUSION

Individuals working in rotating shifts for more than 15 days have significantly higher prevalence of insomnia than day-workers.

Influence of WeChat on sleep quality among undergraduates in Chongqing, China: a cross-sectional study

BACKGROUND

Previous studies showed that social media is associated with sleep quality. WeChat (a native social media in China) is very popular in China, especially among the youth. In the second quarter of 2016, Tencent's WeChat had 806 million monthly active users. The study sought to identify the influence of WeChat on the sleep quality among undergraduate students.

METHODS

A cross-sectional survey adopted a multi-stage stratified sampling survey to investigate undergraduates in Chongqing, China. Data were collected on 1979 eligible adults, aged 20.27 (SD: 1.26) years old, using Pittsburgh Sleep Quality Index (PSQI) to measure sleep quality.

RESULTS

Respondents aged 20.27 ± 1.26 years included 535 (27.0%) males, and 1311 (66.3%) reported as having poor sleep quality. Of the 1979 participants, 1320 (66.70%) were WeChat users. In multivariable analyses, gender, grade, nationality, living costs, the student leader, the only child, type of university, WeChat usage was associated with domains of PSQI among undergraduates (p < 0.05 for all). Compared with non-users, WeChat users had a lower score of subjective quality of sleep, sleep latency, use of sleeping medication, daytime dysfunction, and global PSQI score (p < 0.05 for all).

CONCLUSIONS

WeChat users may have better sleep quality than non-WeChat users among undergraduates. To determine causal relationships, further longitudinal studies will be required to test for the association between WeChat users and sleep quality. This study may also provide some implications for health promotion on sleep quality of undergraduate students.

Can the circadian phase be estimated from self-reported sleep timing in patients with Delayed Sleep Wake Phase Disorder to guide timing of chronobiologic treatment?

INTRODUCTION

The efficacy of bright light and/or melatonin treatment for Delayed Sleep Wake Phase Disorder (DSWPD) is contingent upon an accurate clinical assessment of the circadian phase. However, the process of determining this circadian phase can be costly and is not yet readily available in the clinical setting. The present study investigated whether more cost-effective and convenient estimates of the circadian phase, such as self-reported sleep timing, can be used to predict the circadian phase and guide the timing of light and/or melatonin treatment (i.e. dim-light melatonin onset, core body temperature minimum and melatonin secretion mid-point) in a sample of individuals with DSWPD.

METHOD

Twenty-four individuals (male = 17; mean age = 21.96, SD = 5.11) with DSWPD were selected on the basis of ICSD-3 criteria from a community-based sample. The first 24-hours of a longer 80-hour constant laboratory ultradian routine were used to determine core body temperature minimum (cBT^min), dim-light melatonin onset (DLMO) and the midpoint of the melatonin secretion period (DLM^mid = [DLM°^ff-DLMO]/2). Prior to the laboratory session subjective sleep timing was assessed using a 7-day sleep/wake diary, the Pittsburgh Sleep Quality Index (PSQI), and the Delayed Sleep Phase Disorder Sleep Timing Questionnaire (DSPD-STQ).

RESULTS

Significant moderate to strong positive correlations were observed between self-reported sleep timing variables and DLMO, cBT^min and DLM^mid. Regression equations revealed that the circadian phase (DLMO, cBT^min and DLM^mid) was estimated within ±1.5 hours of the measured circadian phase most accurately by the combination of sleep timing measures (88% of the sample) followed by sleep diary reported midsleep (83% of the sample) and sleep onset time (79% of the sample).

DISCUSSION

These findings suggest that self-reported sleep timing may be useful clinically to predict a therapeutically relevant circadian phase in DSWPD.

Comparative Review of Approved Melatonin Agonists for the Treatment of Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep‐wake disorders (CRSWDs) are characterized by persistent or recurrent patterns of sleep disturbance related primarily to alterations of the circadian rhythm system or the misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep. These disorders collectively represent a significant unmet medical need, with a total prevalence in the millions, a substantial negative impact on quality of life, and a lack of studied treatments for most of these disorders. Activation of the endogenous melatonin receptors appears to play an important role in setting the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Therefore, melatonin agonists, which may be able to shift and/or stabilize the circadian phase, have been identified as potential therapeutic candidates for the treatment of CRSWDs. Currently, only one melatonin receptor agonist, tasimelteon, is approved for the treatment of a CRSWD: non–24‐hour sleep‐wake disorder (or non‐24). However, three additional commercially available melatonin receptor agonists—agomelatine, prolonged‐release melatonin, and ramelteon—have been investigated for potential use for treatment of CRSWDs. Data indicate that these melatonin receptor agonists have distinct pharmacologic profiles that may help clarify their clinical use in CRSWDs. We review the pharmacokinetic and pharmacodynamic properties of these melatonin agonists and summarize their efficacy profiles when used for the treatment of CRSWDs. Further studies are needed to determine the therapeutic potential of these melatonin agonists for most CRSWDs.

Prevention of fatigue and insomnia in shift workers-a review of non-pharmacological measures

Background

Excessive fatigue and insomnia are common among shift workers and can lead to negative effects such as reduced work performance, processing errors, accidents at work, absenteeism, reduced quality of life, and symptoms of depression. Moreover, work in rotating shifts can be a risk factor for different somatic and psychiatric diseases and may contribute to poor health, especially in elder adults and women. This review aims to show non-pharmacological preventive measures against fatigue and insomnia in shift workers.

Method

Computerized literature searches in MedLine and in the Cochrane Library were performed with the following key words: shift work disorder, fatigue, insomnia, shift work, measures, treatment, therapy, strategies and coping. The search was limited to non-pharmacological studies that were conducted on human subjects and published as English-language articles in peer-reviewed journals since 1970. Additional studies were identified through the reference sections of relevant articles. Eighteen articles on fatigue in shift workers, including six original research articles with a total sample size of 3504 probands consisting of industrial workers, office employees, aircraft maintenance engineers, and non-shift workers working in simulated shifts, were analyzed, as well as seven articles on insomnia, including an original research article with a sample size of 26 media workers. Also, 4 reviews on shift work disorder were analyzed.

Main

The occurrence of fatigue and insomnia in shift workers associated with a working period is described as shift work disorder. Estimations on the prevalence of shift work disorder in shift workers vary between 5 % and about 20 %; about one in three shift workers is affected by insomnia and up to 90 % of shift workers report regular fatigue and sleepiness at the workplace. We concluded that there is a necessity for treatments to improve the sleep quality of the shift working population. The most common non-pharmacological recommendations to improve sleep quality and to reduce insomnia and fatigue were scheduling, bright light exposure, napping, psychoeducation for sleep hygiene, and cognitive-behavioral measures.

Conclusion

Some important preventive coping strategies for fatigue associated with shift work such as napping and exposure to bright light have already been investigated and are generally approved. A few studies also provide good evidence for the efficacy of cognitive-behavioral techniques in the treatment of chronic primary and comorbid insomnia. These coping strategies summarized in this paper should be considered in the workplace health promotion programs of each work environment to improve working conditions for shift workers and to save money.

Associations of sleep duration and quality with disinhibited eating behaviors in adolescent girls at-risk for type 2 diabetes

OBJECTIVES

Short sleep duration and daytime sleepiness have been associated with an increased risk for the onset of type 2 diabetes in adults. There has been far less attention to the characterization of sleep in adolescents at-risk for diabetes or to the possible behavioral mechanisms, such as disinhibited eating, through which sleep may affect metabolic functioning.

METHODS

We evaluated the associations of sleep duration and daytime sleepiness with a multi-modal assessment of disinhibited eating in 119 adolescent girls at-risk for type 2 diabetes based upon being overweight/obese and having a family history of diabetes. Girls also endorsed mild-to-moderate depressive symptoms. Adolescents reported sleep duration and daytime sleepiness with the Sleep Habits Survey and Children's Sleep Habits Questionnaire. They were administered a series of successive test meals to measure total energy intake and eating in the absence of hunger (EAH). Adolescent binge eating was assessed with the Eating Disorder Examination interview.

RESULTS

Accounting for age, race, puberty, body composition, depressive symptoms, and perceived stress, reported sleep duration was positively related to test meal total energy intake (p=0.04), but not to EAH. Adjusting for the same covariates, daytime sleepiness was associated with a greater odds of objective binge eating in the previous month (p=0.009).

CONCLUSIONS

In adolescent girls at-risk for type 2 diabetes, reported sleep characteristics are associated with disinhibited eating behaviors that have been linked to excessive weight and adverse metabolic outcomes. Future studies are called for to evaluate these links using objective measures of sleep.

Short Blue Light Pulses (30 Min) in the Morning Support a Sleep-Advancing Protocol in a Home Setting

Many people in our modern civilized society sleep later on free days compared to work days. This discrepancy in sleep timing will lead to so-called 'social jetlag' on work days with negative consequences for performance and health. Light therapy in the morning is often proposed as the most effective method to advance the circadian rhythm and sleep phase. However, most studies focus on direct effects on the circadian system and not on posttreatment effects on sleep phase and sleep integrity. In this placebo-controlled home study we investigated if blue light, rather than amber light therapy, can phase shift the sleep phase along with the circadian rhythm with preservation of sleep integrity and performance. We selected 42 participants who suffered from 'social jetlag' on workdays. Participants were randomly assigned to either high-intensity blue light exposure or amber light exposure (placebo) with similar photopic illuminance. The protocol consisted of 14 baseline days without sleep restrictions, 9 treatment days with either 30-min blue light pulses or 30-min amber light pulses in the morning along with a sleep advancing scheme and 7 posttreatment days without sleep restrictions. Melatonin samples were taken at days 1, 7, 14 (baseline), day 23 (effect treatment), and day 30 (posttreatment). Light exposure was recorded continuously. Sleep was monitored through actigraphy. Performance was measured with a reaction time task. As expected, the phase advance of the melatonin rhythm from day 14 to day 23 was significantly larger in the blue light exposure group, compared to the amber light group (84 min ± 51 (SD) and 48 min ± 47 (SD) respectively; t36 = 2.23, p < 0.05). Wake-up time during the posttreatment days was slightly earlier compared to baseline in the blue light group compared to slightly later in the amber light group (-21 min ± 33 (SD) and +12 min ± 33 (SD) respectively; F1,35 = 9.20, p < 0.01). The number of sleep bouts was significantly higher in the amber light group compared to the blue light group during sleep in the treatment period (F1,32 = 4.40, p < 0.05). Performance was significantly worse compared to baseline at all times during (F1,13 = 10.1, p < 0.01) and after amber light treatment (F1,13 = 17.1, p < 0.01), while only in the morning during posttreatment in the blue light condition (F1,10 = 9.8, p < 0.05). The data support the conclusion that blue light was able to compensate for the sleep integrity reduction and to a large extent for the performance decrement that was observed in the amber light condition, both probably as a consequence of the advancing sleep schedule. This study shows that blue light therapy in the morning, applied in a home setting, supports a sleep advancing protocol by phase advancing the circadian rhythm as well as sleep timing.

Effects of a sleep education program with self-help treatment on sleeping patterns and daytime sleepiness in Japanese adolescents: A cluster randomized trial

Subjective insufficient sleep and delayed sleep-wake patterns have been reported as the primary causes for daytime sleepiness, a reasonably significant and prevalent problem for adolescents worldwide. Systematic reviews have indicated that the success of sleep education programs has thus far been inconsistent, due to the lack of a tailored approach that allows for evaluation of individual differences in behavior patterns. One way to resolve this problem is to assess the individual sleep behaviors of adolescents by using a checklist containing the recommended behaviors for promoting sleep health. Such self-help education programs have already been implemented for elementary school children, school nurses and the elderly. The present study aimed to verify the effects of a sleep education program with supplementary self-help treatment, based on a checklist of sleep-promoting behaviors, in addition to evaluation of changes in sleeping patterns, sleep-promoting behaviors and daytime sleepiness in adolescents. A cluster randomized controlled trial involving 5 Japanese junior high schools was conducted, and 243 students (sleep education: n = 122; waiting list: n = 121; 50.6% female; 7th grade) were included in the final analysis. The sleep education group was provided with information on proper sleep health and sleep-promoting behaviors. The students in this group were asked to practice one sleep-promoting behavior as a goal for 2 weeks and to monitor their practice using sleep diaries. Both pre- and post-treatment questionnaires were administered to students in order to assess knowledge of sleep-promoting behaviors, sleeping patterns and daytime functioning. Students in the sleep education group showed significant improvement in their knowledge of sleep health (F1,121 = 648.05, p < 0.001) and in their sleep-promoting behaviors (F1,121 = 55.66, p < 0.001). Bedtime on both school nights (F1,121 = 50.86, p < 0.001) and weekends (F1,121 = 15.03, p < 0.001), sleep-onset latency (F1,121 = 10.26, p = 0.002), total sleep time on school nights (F1,121 = 12.45, p = 0.001), subjective experience of insufficient sleep (McNemar χ(2)(1) = 4.03, p = 0.045) and daytime sleepiness (McNemar χ(2)(1) = 4.23, p = 0.040) were also improved in the sleep education group. In contrast, no significant improvement in these variables was observed for students in the waiting-list group. In conclusion, the sleep education program with self-help treatment was effective not only in increasing sleep knowledge but also in improving sleep-promoting behavior and sleeping patterns/reducing daytime sleepiness for students in the sleep education group, in comparison with the waiting-list group.

Cognitive Behavioral Therapy as an Adjunct Treatment to Light Therapy for Delayed Sleep Phase Disorder in Young Adults: A Randomized Controlled Feasibility Study

Delayed sleep phase disorder (DSPD) is common among young people, but there is still no evidence-based treatment available. In the present study, the feasibility of cognitive behavioral therapy (CBT) was evaluated as an additive treatment to light therapy (LT) in DSPD. A randomized controlled trial with participants aged 16 to 26 years received LT for two weeks followed by either four weeks of CBT or no treatment (NT). LT advanced sleep-wake rhythm in both groups. Comparing LT+CBT with LT+NT, no significant group differences were observed in the primary endpoints. Although anxiety and depression scores were low at pretreatment, they decreased significantly more in LT+CBT compared to LT+NT. The results are discussed and some suggestions are given for further studies.

Chronobiological types, duration of sleeping and psycho-emotional condition of teenagers

Sleep is a biological process that operates according to day and night cycles. This self-regulatory system is universal in all organisms, including humans and mammals. For this reason, the topic is widely analysed in the existing literature; however, no studies about chronobiological types of teenagers have been conducted in Lithuania before. 253 schoolchildren, 13 to 18 years of age, were surveyed in schools of Vilnius and Panevėžys, Lithuania. Responses were gathered during the period from September 2013 to February 2014. The survey consists of four parts: demographical data, Morningness-Eveningness Questionnaire, PedsQL 4.0 survey of life quality, and HADS - Hospital Anxiety and Depression Survey. In total, 115 (45.5%) boys and 138 (54.5%) girls participated in the survey. On average, boys sleep 7.10 (±1.27) hours, compared to 6.79 (±1.20) (p = 0.05) hours for girls. 94 (37.2%) survey participants feel sleepy and/or very sleepy at school. 133 (52.6%) respondents find it difficult/very difficult to wake up in the morning. 218 (86.2%) respondents use the computer before going to sleep: 96 (83.5%) boys and 122 (88.4%) girls. Based on a subjective evaluation, 187 (73.9%) respondents categorize themselves as the evening type and 66 (26.1%) as the morning type. 13 (5.1%) respondents exhibit symptoms of depression. The majority of the respondents categorize themselves as evening/middle chronotypes. The average duration of sleep is 6.93 (±1.24) hours. 86.2% of the respondents use the computer before going to sleep. Half of the children may have difficulties waking up in the morning. One out of three children feels sleepy at school.

Circadian rest-activity rhythm in individuals at risk for psychosis and bipolar disorder

BACKGROUND

At-risk mental states (ARMS) are clinical syndromes that are associated with higher risk, compared with the general population, for developing psychosis and bipolar disorder. Circadian rhythm misalignments have been proposed to be part of this early phase of the clinical course.

OBJECTIVE

To compare circadian rhythm of activity and rest changes between ARMS individuals and a healthy control group.

METHODS

Forty volunteers of both genders, aged between 13 and 27years old, participated in this study (n=20 ARMS group, and n=20 healthy controls). The ARMS individuals were classified as ultra-high risk for psychosis according to the CAARMS (Comprehensive Assessment of At-risk Mental State) or at high risk for bipolar disorder according to criteria proposed by Bechdolf and colleagues. Participants used an actigraph for fifteen days, kept a sleep diary, and completed the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, and a Morningness-Eveningness Questionnaire.

RESULTS

Compared with healthy volunteers, the ARMS group presented worse sleep quality (P=0.010); longer nap durations (P=0.038), shorter wake times (P=0.001), higher total sleep times (P=0.011), and shorter activity duration (P=0.021), sleep rhythms were more fragmented, the circadian rest-activity rhythms were less synchronized with the dark-light cycle and had lower amplitudes of motor activity.

CONCLUSION

The results suggest alterations in the circadian rest-activity rhythms (and likely in sleep-wake cycle patterns) in ARMS individuals compared with healthy controls. It is possible that circadian rhythms of activity and rest changes are one of the prodromal clinical and behavioral expressions of the brain changes that underlie ARMS individuals.

The effects of light therapy on sleep problems: A systematic review and meta-analysis

Although bright light therapy seems a promising treatment for sleep problems, research shows inconclusive results. This meta-analysis is the first to systematically review the effect of light therapy on sleep problems in general and on specific types of sleep problems in particular (circadian rhythm sleep disorders, insomnia, sleep problems related to Alzheimer's disease and dementia). Fifty-three studies with a total of 1154 participants were included. Overall effects and effects on separate circadian and sleep outcomes were examined. We calculated Hedges' g effect sizes and we investigated the effects of twelve moderators (design-related, treatment-related, participant-related). Light therapy was found effective in the treatment of sleep problems in general (g = 0.39), and for circadian rhythm sleep disorders (g = 0.41), insomnia (g = 0.47), and sleep problems related to Alzheimer's disease/dementia (g = 0.30) specifically. For circadian rhythm sleep disorders, effects were smaller for randomised controlled trials. For insomnia, we found larger effects for studies using a higher light intensity, and for sleep problems related to Alzheimer's disease/dementia larger effects were found for studies with more female participants. There was indication of publication bias. To conclude, light therapy is effective for sleep problems in general, particularly for circadian outcomes and insomnia symptoms. However, most effect sizes are small to medium.

Circadian Modulation of 8-Oxoguanine DNA Damage Repair

The DNA base excision repair pathway is the main system involved in the removal of oxidative damage to DNA such as 8-Oxoguanine (8-oxoG) primarily via the 8-Oxoguanine DNA glycosylase (OGG1). Our goal was to investigate whether the repair of 8-oxoG DNA damage follow a circadian rhythm. In a group of 15 healthy volunteers, we found a daily variation of Ogg1 expression and activity with higher levels in the morning compared to the evening hours. Consistent with this, we also found lower levels of 8-oxoG in morning hours compared to those in the evening hours. Lymphocytes exposed to oxidative damage to DNA at 8:00 AM display lower accumulation of 8-oxoG than lymphocytes exposed at 8:00 PM. Furthermore, altered levels of Ogg1 expression were also observed in a group of shift workers experiencing a deregulation of circadian clock genes compared to a control group. Moreover, BMAL1 knockdown fibroblasts with a deregulated molecular clock showed an abolishment of circadian variation of Ogg1 expression and an increase of OGG1 activity. Our results suggest that the circadian modulation of 8-oxoG DNA damage repair, according to a variation of Ogg1 expression, could render humans less susceptible to accumulate 8-oxoG DNA damage in the morning hours.

Excessive daytime sleepiness in patients with ADHD--diagnostic and management strategies

The links between attention-deficit hyperactivity disorder (ADHD) and sleep disorders remain unclear. Specific sleep disorders are a frequent comorbid condition associated with ADHD according to a categorical approach. However, sleep disorders can also induce ADHD-like symptoms according to a dimensional approach and are thought to be the consequence of excessive daytime sleepiness. It may thus be difficult for clinicians to differentiate the diagnosis of ADHD comorbid with a sleep disorder from sleep disorders with ADHD-like symptoms. This distinction could be important for the appropriate management of patients with dual complaints of trouble maintaining attention and daytime sleepiness. This paper summarizes the main sleep disorders associated with ADHD: sleep-related breathing disorders, sleep-related movement disorders, circadian rhythm sleep-wake disorders, and central disorders of hypersomnolence (aka hypersomnias). The history of presenting symptoms should be taken into account since ADHD is a neurodevelopmental disorder whereas ADHD symptoms comorbid with sleep disorder are not. Finally, we propose a model to clarify the links between ADHD, ADHD symptoms, and excessive daytime sleepiness induced by sleep disorders. Clinicians should therefore routinely assess, monitor, and manage the sleep problems of patients with ADHD who have both comorbidities and should search for the presence of ADHD symptoms in subjects with sleep disorders.

Chronic shifts in the length and phase of the light cycle increase intermittent alcohol drinking in C57BL/6J mice

Introduction: Shift workers—e.g., health care professionals, truck drivers, and factory workers—are forced to maintain daily cycles at odds with their natural circadian rhythms and as a consequence need to frequently readjust these cycles. This shift work-induced circadian desynchrony (CD) is associated with increased sleep disorders and with alcohol abuse. Nonetheless, it has proven difficult to model CD-induced changes in alcohol consumption in mouse models, which is an important step toward identifying the mechanisms by which CD increases alcohol intake. This study examined whether frequent changes in the light cycle could increase free access alcohol intake in a mouse line that readily consumes alcohol.

Methods: Free access alcohol intake, water intake, and wheel-running activity patterns of male C57BL/6J mice were measured while the mice were maintained on a normal 12HR photoperiod for baseline data for 2 weeks. The mice were then exposed to an alternating photoperiod of 12 h and 18 h, with light onset advanced 8 h during the 18HR photoperiod. The photoperiods rotated every 3 days, for 21 days total.

Results: The repeated pattern of phase advances and delays, with a concurrent change in the length of the photoperiod, shifted mice to a pattern of intermittent alcohol drinking without altering water intake. Wheel running activity demonstrated that mice were unable to reset their behavioral clocks during CD, showing constant, low-level activity with no peak in activity at the start of the dark phase and greater activity during the morning light phase.

Conclusion: It is possible to model CD effects on alcohol intake in C57BL/6J mice using a pattern of phase shifts and changes in the photoperiod. Using this model, we demonstrate that mice begin intermittent drinking during CD, and this increase in alcohol intake does not correlate with an increase in overall activity or in overall fluid intake.

Millisecond flashes of light phase delay the human circadian clock during sleep

The human circadian timing system is most sensitive to the phase-shifting effects of light during the biological nighttime, a time at which humans are most typically asleep. The overlap of sleep with peak sensitivity to the phase-shifting effects of light minimizes the effectiveness of using light as a countermeasure to circadian misalignment in humans. Most current light exposure treatments for such misalignment are mostly ineffective due to poor compliance and secondary changes that cause sleep deprivation. Using a 16-day, parallel group design, we examined whether a novel sequence of light flashes delivered during sleep could evoke phase changes in the circadian system without disrupting sleep. Healthy volunteers participated in a 2-week circadian stabilization protocol followed by a 2-night laboratory stay. During the laboratory session, they were exposed during sleep to either darkness (n = 7) or a sequence of 2-msec light flashes given every 30 sec (n = 6) from hours 2 to 3 after habitual bedtime. Changes in circadian timing (phase) and micro- and macroarchitecture of sleep were assessed. Subjects exposed to the flash sequence during sleep exhibited a delay in the timing of their circadian salivary melatonin rhythm compared with the control dark condition (p < 0.05). Confirmation that the flashes penetrated the eyelids is presented by the occurrence of an evoked response in the EEG. Despite the robust effect on circadian timing, there were no large changes in either the amount or spectral content of sleep (p values > 0.30) during the flash stimulus. Exposing sleeping individuals to 0.24 sec of light spread over an hour shifted the timing of the circadian clock and did so without major alterations to sleep itself. While a greater number of matched subjects and more research will be necessary to ascertain whether these light flashes affect sleep, our data suggest that this type of passive phototherapy might be developed as a useful treatment for circadian misalignment in humans.

Daytime Sleepiness, Circadian Preference, Caffeine Consumption and Use of Other Stimulants among Thai College Students

We conducted this study to evaluate the prevalence of daytime sleepiness and evening chronotype, and to assess the extent to which both are associated with the use of caffeinated stimulants among 3,000 Thai college students. Demographic and behavioral characteristics were collected using a self-administered questionnaire. The Epworth Sleepiness Scale and the Horne and Ostberg Morningness-Eveningness Questionnaire were used to evaluate prevalence of daytime sleepiness and circadian preference. Multivariable logistic regression models were used to evaluate the association between sleep disorders and consumption of caffeinated beverages. Overall, the prevalence of daytime sleepiness was 27.9 % (95% CI: 26.2-29.5%) while the prevalence of evening chronotype was 13% (95% CI: 11.8-14.2%). Students who use energy drinks were more likely to be evening types. For instance, the use of M100/M150 energy drinks was associated with a more than 3-fold increased odds of evening chronotype (OR 3.50; 95% CI 1.90-6.44), while Red Bull users were more than twice as likely to have evening chronotype (OR 2.39; 95% CI 1.02-5.58). Additionally, those who consumed any energy drinks were more likely to be daytime sleepers. For example, Red Bull (OR 1.72; 95% CI 1.08-2.75) or M100/M150 (OR 1.52; 95% CI 1.10-2.11) consumption was associated with increased odds of daytime sleepiness. Our findings emphasize the importance of implementing educational and prevention programs targeted toward improving sleep hygiene and reducing the consumption of energy drinks among young adults.

Rest-Activity Cycle Disturbances in the Acute Phase of Moderate to Severe Traumatic Brain Injury

Background. Sleep-wake disturbances are among the most persistent sequelae after traumatic brain injury (TBI) and probably arise during the hospital stay following TBI. These disturbances are characterized by difficulties sleeping at night and staying awake during the day. Objective. The aim of the present study was to document rest-activity cycle consolidation in acute moderate/severe TBI using actigraphy and to assess its association with injury severity and outcome. Methods. In all, 16 hospitalized patients (27.1 ± 11.3 years) with moderate/severe TBI wore actigraphs for 10 days, starting in the intensive care unit (ICU) when continuous sedation was discontinued and patients had reached medical stability. Activity counts were summed for daytime (7:00-21:59 hours) and nighttime periods (22:00-6:59 hours). The ratio of daytime period activity to total 24-hour activity was used to quantify rest-activity cycle consolidation. An analysis of variance was carried out to characterize the evolution of the daytime activity ratio over the recording period. Results. Rest-activity cycle was consolidated only 46.6% of all days; however, a significant linear trend of improvement was observed over time. Greater TBI severity and longer ICU and hospital lengths of stay were associated with poorer rest-activity cycle consolidation and evolution. Patients with more rapid return to consolidated rest-activity cycle were more likely to have cleared posttraumatic amnesia and have lower disability at hospital discharge. Conclusions. Patients with acute moderate/severe TBI had an altered rest-activity cycle, probably reflecting severe fragmentation of sleep and wake episodes, which globally improved over time. A faster return to rest-activity cycle consolidation may predict enhanced brain recovery.

Circadian rhythm disorders among adolescents: assessment and treatment options

Delayed sleep phase disorder (DSPD) - a circadian rhythm sleep disorder - is most commonly seen in adolescents. The differential diagnosis between DSPD and conventional psychophysiological insomnia is important for correct therapeutic intervention. Adolescent DSPD sleep duration is commonly 9 hours or more. Depression may be comorbid with DSPD. DSPD has a negative impact on adolescent academic performance. DSPD treatments include bright light therapy, chronotherapeutic regimens, and administration of melatonin as a chronobiotic (as distinct from a soporific). Attention to non-photic and extrinsic factors including healthy sleep parameters is also important to enable better sleep and mood outcomes in adolescents.

How to fix a broken clock

Fortunate are those who rise out of bed to greet the morning light well rested with the energy and enthusiasm to drive a productive day. Others, however, depend on hypnotics for sleep and require stimulants to awaken lethargic bodies. Sleep/wake disruption is a common occurrence in healthy individuals throughout their lifespan and is also a comorbid condition to many diseases (neurodegenerative) and psychiatric disorders (depression and bipolar). There is growing concern that chronic disruption of the sleep/wake cycle contributes to more serious conditions including diabetes (type 2), cardiovascular disease, and cancer. A poorly functioning circadian system resulting in misalignments in the timing of clocks throughout the body may be at the root of the problem for many people. In this article we discuss environmental (light therapy) and lifestyle changes (scheduled meals, exercise, and sleep) as interventions to help fix a broken clock. We also discuss the challenges and potential for future development of pharmacological treatments to manipulate this key biological system.

Circadian Rhythm Sleep Disorders

OBJECTIVE

To review circadian rhythm sleep disorders, including underlying causes, diagnostic considerations, and typical treatments.

METHODS

Literature review and discussion of specific cases.

RESULTS

Survey studies ^1,2 suggest that up to 3% of the adult population suffers from a circadian rhythm sleep disorder (CRSD). However, these sleep disorders are often confused with insomnia, and an estimated 10% of adult and 16% of adolescent sleep disorders patients may have a CRSD ^3-6. While some CRSD (such as jet lag) can be self-limiting, others when untreated can lead to adverse medical, psychological, and social consequences. The International Classification of Sleep Disorders classifies CRSD as dyssomnias, with six subtypes: Advanced Sleep Phase Type, Delayed Sleep Phase Type, Irregular Sleep Wake Type, Free Running Type, Jet Lag Type, and Shift Work Type. The primary clinical characteristic of all CRSD is an inability to fall asleep and wake at the desired time. It is believed that CRSD arise from a problem with the internal biological clock (circadian timing system) and/or misalignment between the circadian timing system and the external 24-hour environment. This misalignment can be the result of biological and/or behavioral factors. CRSD can be confused with other sleep or medical disorders.

CONCLUSIONS

Circadian rhythm sleep disorders are a distinct class of sleep disorders characterized by a mismatch between the desired timing of sleep and the ability to fall asleep and remain asleep. If untreated, CRSD can lead to insomnia and excessive daytime sleepiness, with negative medical, psychological, and social consequences. It is important for physicians to recognize potential circadian rhythm sleep disorders so that appropriate diagnosis, treatment, and referral can be made.

In vitro circadian period is associated with circadian/sleep preference

Evaluation of circadian phenotypes is crucial for understanding the pathophysiology of diseases associated with disturbed biological rhythms such as circadian rhythm sleep disorders (CRSDs). We measured clock gene expression in fibroblasts from individual subjects and observed circadian rhythms in the cells (in vitro rhythms). Period length of the in vitro rhythm (in vitro period) was compared with the intrinsic circadian period, τ, measured under a forced desynchrony protocol (in vivo period) and circadian/sleep parameters evaluated by questionnaires, sleep log, and actigraphy. Although no significant correlation was observed between the in vitro and in vivo periods, the in vitro period was correlated with chronotype, habitual sleep time, and preferred sleep time. Our data demonstrate that the in vitro period is significantly correlated with circadian/sleep preference. The findings suggest that fibroblasts from individual patients can be utilized for in vitro screening of therapeutic agents to provide personalized therapeutic regimens for CRSD patients.

Trying to fall asleep while catastrophising: what sleep-disordered adolescents think and feel

OBJECTIVE

Catastrophising is a repetitive cognitive process related to sleep disturbance in adult insomnia patients. More recently catastrophising has been associated with increased sleep disturbances in community samples of children and adolescents, with this association mediated by anxiety and depression. However, there currently is no evidence of these processes outside of community samples; impeding our ability to draw clinical conclusions. Knowledge on such dysfunctional cognitive processes in adolescents experiencing sleep disturbance would be clinically beneficial in aetiology and intervention. Our research examined the link between catastrophising, anxiety, depression and sleep latency in a sample of sleep-disordered adolescents. We also explored specific catastrophising themes which may impact the sleep latency of these adolescents.

METHOD

Forty adolescents (age=15.1±1.5 years, 53% boys) diagnosed with delayed sleep phase disorder completed a 7-day sleep diary, along with measures of anxiety and depression and a catastrophising interview with a trained sleep therapist.

RESULTS

Several catastrophisation themes were generated, the most common concerning interpersonal and performance aspects of school. Bootstrapping analyses showed depression did not mediate the relationship between catastrophising and sleep; however, an indirect relationship was found between catastrophising, anticipatory anxiety, and sleep latency.

CONCLUSION

These findings have implications for the role of dysfunctional thinking in prolonging sleep onset for adolescents and providing a clinical framework for health professionals when assessing and treating adolescents with delayed sleep timing.

Chronic insomnia

PURPOSE OF REVIEW

This article provides an overview of current strategies for evaluating and treating patients who experience chronic insomnia.

RECENT FINDINGS

The US Food and Drug Administration (FDA) has approved several medications for the treatment of insomnia that incorporate a variety of pharmacodynamic and pharmacokinetic properties, thus allowing the development of a customized therapeutic approach. FDA-approved medications include γ-aminobutyric acid-modulating benzodiazepine receptor agonists, a melatonin receptor agonist, and a histamine receptor agonist. Psychological and behavioral techniques combined as cognitive-behavioral therapy also have been shown to be effective in the treatment of chronic insomnia.

SUMMARY

Insomnia is the most common sleep disturbance and represents a chronic condition for many people. Difficulty falling asleep and maintaining sleep are highly prevalent problems in patients with neurologic disorders. Multiple factors typically contribute to insomnia. Accordingly, a rather broad approach to evaluating patients is warranted. Evidence-based guidelines support the use of cognitive and behavioral strategies and selected medications in the treatment of patients with chronic insomnia.

Association between Facebook dependence and poor sleep quality: a study in a sample of undergraduate students in Peru

Objectives

Internet can accelerate information exchange. Social networks are the most accessed especially Facebook. This kind of networks might create dependency with several negative consequences in people’s life. The aim of this study was to assess potential association between Facebook dependence and poor sleep quality.

Methodology/Principal Findings

A cross sectional study was performed enrolling undergraduate students of the Universidad Peruana de Ciencias Aplicadas, Lima, Peru. The Internet Addiction Questionnaire, adapted to the Facebook case, and the Pittsburgh Sleep Quality Index, were used. A global score of 6 or greater was defined as the cutoff to determine poor sleep quality. Generalized linear model were used to determine prevalence ratios (PR) and 95% confidence intervals (95%CI). A total of 418 students were analyzed; of them, 322 (77.0%) were women, with a mean age of 20.1 (SD: 2.5) years. Facebook dependence was found in 8.6% (95% CI: 5.9%–11.3%), whereas poor sleep quality was present in 55.0% (95% CI: 50.2%–59.8%). A significant association between Facebook dependence and poor sleep quality mainly explained by daytime dysfunction was found (PR = 1.31; IC95%: 1.04–1.67) after adjusting for age, sex and years in the faculty.

Conclusions

There is a relationship between Facebook dependence and poor quality of sleep. More than half of students reported poor sleep quality. Strategies to moderate the use of this social network and to improve sleep quality in this population are needed.

Short wavelength light administered just prior to waking: a pilot study

Bright light in the blue-green range, administered in the early morning hours (prior to waking) may be particularly effective in shifting circadian rhythms and may increase gonadotropin production. Accordingly, we tested the feasibility and utility of a mask that emits bright blue/green light (compared to a similar mask that emitted a dim red light) towards the end of sleep in a randomized, placebo-controlled pilot study. The study included a 3-day baseline period, immediately followed by a 12-day intervention period. Subjects were 30 healthy young men with minimal-mild depression. The bright light masks were well-tolerated and demonstrated adequate safety and feasibility. Following the intervention, those who wore the bright light mask demonstrated altered sleep timing suggestive of an earlier sleep period, and excreted a slight increase in follicle-stimulating hormone. Overall, light masks may prove useful in future studies of bright light therapy.

Intrinsic circadian period of sighted patients with circadian rhythm sleep disorder, free-running type

BACKGROUND

Circadian rhythm sleep disorder, free-running type (FRT), is an intractable sleep disorder in which sleep and wake times progressively delay each day even in normal living environments. This disorder severely affects the social functioning of patients because of periodic nighttime insomnia, excessive daytime sleepiness, and a high rate of comorbid psychiatric disorders. Although abnormal regulation of the biological clock is suspected, the pathophysiology of FRT has yet to be elucidated. In this study, the endogenous circadian period, τ, of FRT patients with normal vision was compared with that of healthy individuals whose circadian rhythms are entrained to a 24-hour cycle.

METHODS

Six FRT patients and 17 healthy individuals (9 intermediate chronotypes and 8 evening chronotypes) were subjected to a 7-day, 28-hour sleep-wake schedule according to the forced desynchrony protocol. Phase shifts in melatonin rhythm were measured under constant routine conditions to calculate τ.

RESULTS

In FRT patients, τ was significantly longer than in intermediate chronotypes, whereas in evening chronotypes, it ranged widely and was not significantly different from that in FRT patients. Moreover, τ of melatonin rhythm in FRT patients showed no significant correlation with τ of sleep-wake cycles measured before the study.

CONCLUSIONS

The findings suggest that although a prolongation of τ may be involved in the onset mechanism of FRT, a prolonged τ is not the only factor involved. It appears that several factors including abnormal entrainment of circadian rhythms are involved in the onset of FRT in a multilayered manner.

Parasomnias: an updated review

Parasomnias are abnormal behaviors emanating from or associated with sleep. Sleepwalking and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, or promote sleep inertia lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after an arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications; in particular, the widely prescribed benzodiazepine receptor agonists. Recently, compelling evidence suggests that nocturnal eating may in some cases be a nonmotor manifestation of Restless Legs Syndrome (RLS). rapid eye movement (REM) Sleep Behavior Disorder (RBD) is characterized by a loss of REM paralysis leading to potentially injurious dream enactment. The loss of atonia in RBD often predates the development of Parkinson's disease and other disorders of synuclein pathology. Parasomnia behaviors are related to an activation (in NREM parasomnias) or a disinhibition (in RBD) of central pattern generators (CPGs). Initial management should focus on decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders. Clonazepam and melatonin appear to be effective therapies in RBD, whereas paroxetine has been reported effective in some cases of sleep terrors. At this point, pharmacotherapy for other parasomnias is less certain, and further investigations are necessary.

Rhythmic expression of circadian clock genes in human leukocytes and beard hair follicle cells

Evaluating individual circadian rhythm traits is crucial for understanding the human biological clock system. The present study reports characterization of physiological and molecular parameters in 13 healthy male subjects under a constant routine condition, where interfering factors were kept to minimum. We measured hormonal secretion levels and examined temporal expression profiles of circadian clock genes in peripheral leukocytes and beard hair follicle cells. All 13 subjects had prominent daily rhythms in melatonin and cortisol secretion. Significant circadian rhythmicity was found for PER1 in 9 subjects, PER2 in 3 subjects, PER3 in all 13 subjects, and BMAL1 in 8 subjects in leukocytes. Additionally, significant circadian rhythmicity was found for PER1 in 5 of 8 subjects tested, PER2 in 2 subjects, PER3 in 6 subjects, and BMAL1 in 3 subjects in beard hair follicle cells. The phase of PER1 and PER3 rhythms in leukocytes correlated significantly with that of physiological rhythms. Our results demonstrate that leukocytes and beard hair follicle cells possess an endogenous circadian clock and suggest that PER1 and PER3 expression would be appropriate biomarkers and hair follicle cells could be a useful tissue source for the evaluation of biological clock traits in individuals.

Melatonin treatment in children with therapy-resistant monosymptomatic nocturnal enuresis

OBJECTIVE

To evaluate the effects of exogenous melatonin on the frequency of wet nights, on the sleep-wake cycle, and on the melatonin profile in children with therapy-resistant MNE.

PATIENTS AND METHODS

24 patients were included. Patients had to maintain a diary including time of sleep and arousal, and whether they had a dry or a wet bed in the morning. We measured baseline melatonin profiles in saliva. Hereafter, patients were randomized to synthetic melatonin or placebo. After 3 and 6 months we evaluated the frequency of enuresis and the melatonin profiles.

RESULTS

11 patients were randomized to melatonin, 13 to placebo. We evaluated melatonin profiles of 7 patients in the melatonin group and of 8 in the placebo group. We observed a change in profile in the melatonin group, but we did not observe a difference in the sleep-wake cycle or the frequency of wet nights in either group.

CONCLUSION

This is the first time exogenous melatonin has been evaluated in the treatment of MNE. Although we observed a change in melatonin profile after the use of exogenous melatonin, we did not observe a change in enuresis frequency or in the sleep-wake cycle of this select group of patients.

The neuroendocrine control of the circadian system: adolescent chronotype

Scientists, public health and school officials are paying growing attention to the mechanism underlying the delayed sleep patterns common in human adolescents. Data suggest that a propensity towards evening chronotype develops during puberty, and may be caused by developmental alterations in internal daily timekeeping. New support for this theory has emerged from recent studies which show that pubertal changes in chronotype occur in many laboratory species similar to human adolescents. Using these species as models, we find that pubertal changes in chronotype differ by sex, are internally generated, and driven by reproductive hormones. These chronotype changes are accompanied by alterations in the fundamental properties of the circadian timekeeping system, including endogenous rhythm period and sensitivity to environmental time cues. After comparing the developmental progression of chronotype in different species, we propose a theory regarding the ecological relevance of adolescent chronotype, and provide suggestions for improving the sleep of human adolescents.

Pathophysiology and pathogenesis of circadian rhythm sleep disorders

Metabolic, physiological and behavioral processes exhibit 24-hour rhythms in most organisms, including humans. These rhythms are driven by a system of self-sustained clocks and are entrained by environmental cues such as light-dark cycles as well as food intake. In mammals, the circadian clock system is hierarchically organized such that the master clock in the suprachiasmatic nuclei of the hypothalamus integrates environmental information and synchronizes the phase of oscillators in peripheral tissues. The transcription and translation feedback loops of multiple clock genes are involved in the molecular mechanism of the circadian system. Disturbed circadian rhythms are known to be closely related to many diseases, including sleep disorders. Advanced sleep phase type, delayed sleep phase type and nonentrained type of circadian rhythm sleep disorders (CRSDs) are thought to result from disorganization of the circadian system. Evaluation of circadian phenotypes is indispensable to understanding the pathophysiology of CRSD. It is laborious and costly to assess an individual's circadian properties precisely, however, because the subject is usually required to stay in a laboratory environment free from external cues and masking effects for a minimum of several weeks. More convenient measurements of circadian rhythms are therefore needed to reduce patients' burden. In this review, we discuss the pathophysiology and pathogenesis of CRSD as well as surrogate measurements for assessing an individual's circadian phenotype.

A randomized controlled trial of cognitive-behavior therapy plus bright light therapy for adolescent delayed sleep phase disorder

OBJECTIVE

To evaluate cognitive-behavior therapy plus bright light therapy (CBT plus BLT) for adolescents diagnosed with delayed sleep phase disorder (DSPD).

DESIGN

Randomized controlled trial of CBT plus BLT vs. waitlist (WL) control with comparisons at pre- and post-treatment. There was 6-month follow-up for the CBT plus BLT group only.

SETTING

Flinders University Child & Adolescent Sleep Clinic, Adelaide, South Australia.

PATIENTS

49 adolescents (mean age 14.6 ± 1.0 y, 53% males) diagnosed with DSPD; mean chronicity 4 y 8 months; 16% not attending school. Eighteen percent of adolescents dropped out of the study (CBT plus BLT: N = 23 vs. WL: N = 17).

INTERVENTIONS

CBT plus BLT consisted of 6 individual sessions, including morning bright light therapy to advance adolescents' circadian rhythms, and cognitive restructuring and sleep education to target associated insomnia and sleep hygiene.

MEASUREMENTS AND RESULTS

DSPD diagnosis was performed via a clinical interview and 7-day sleep diary. Measurements at each time-point included online sleep diaries and scales measuring sleepiness, fatigue, and depression symptoms. Compared to WL, moderate-to-large improvements (d = 0.65-1.24) were found at post-treatment for CBT plus BLT adolescents, including reduced sleep latency, earlier sleep onset and rise times, total sleep time (school nights), wake after sleep onset, sleepiness, and fatigue. At 6-month follow-up (N = 15), small-to-large improvements (d = 0.24-1.53) continued for CBT plus BLT adolescents, with effects found for all measures. Significantly fewer adolescents receiving CBT plus BLT met DPSD criteria at post-treatment (WL = 82% vs. CBT plus BLT = 13%, P < 0.0001), yet 13% still met DSPD criteria at the 6-month follow-up.

CONCLUSIONS

CBT plus BLT for adolescent DSPD is effective for improving multiple sleep and daytime impairments in the immediate and long-term. Studies evaluating the treatment effectiveness of each treatment component are needed.

CLINICAL TRIAL INFORMATION

Australia-New Zealand Trials Registry Number: ACTRN12610001041044.

Delayed sleep phase syndrome is related to seasonal affective disorder

BACKGROUND

Both delayed sleep phase syndrome (DSPS) and seasonal affective disorder (SAD) may manifest similar delayed circadian phase problems. However, the relationships and co-morbidity between the two conditions have not been fully studied. The authors examined the comorbidity between DSPS and SAD.

METHODS

We recruited a case series of 327 DSPS and 331 controls with normal sleep, roughly matched for age, gender, and ancestry. Both DSPS and controls completed extensive questionnaires about sleep, the morningness-eveningness trait, depression, mania, seasonality of symptoms, etc.

RESULTS

The prevalences of SAD and subsyndromal SAD (S-SAD) were higher in DSPS compared to controls (χ(2)=12.65, p=0.002). DSPS were 3.3 times more likely to report SAD (odds ratio, 3.34; 95% CI, 1.41-7.93) compared to controls as defined by the Seasonal Pattern Assessment Questionnaire (SPAQ). Correspondingly, DSPS showed significantly higher seasonality scores compared to controls in mood, appetite, and energy level subscores and the global seasonality score (t=3.12, t=0.002; t=2.04, p=0.041; t=2.64, p=0.008; and t=2.15, p=0.032, respectively). Weight fluctuation during seasons and winter-summer sleep length differences were also significantly higher in DSPS than controls (t=5.16, p<0.001 and t=2.64, p=0.009, respectively). SAD and S-SAD reported significantly higher eveningness, higher depression self-ratings, and more previous mania symptoms compared to non-seasonal subjects regardless of whether they were DSPS or controls.

CONCLUSIONS

These cases suggested that DSPS is partially comorbid with SAD. These data support the hypothesis that DSPS and SAD may share a pathophysiological mechanism causing delayed circadian phase.

Dynamics of coupled repressilators: the role of mRNA kinetics and transcription cooperativity

Oscillatory regulatory networks have been discovered in many cellular pathways. An especially challenging area is studying dynamics of cellular oscillators interacting with one another in a population. Synchronization is only one of and the simplest outcome of such interaction. It is suggested that the outcome depends on the structure of the network. Phase-attractive (synchronizing) and phase-repulsive coupling structures were distinguished for regulatory oscillators. In this paper, we question this separation. We study an example of two interacting repressilators (artificial regulatory oscillators based on cyclic repression). We show that changing the cooperativity of transcription repression (Hill coefficient) and reaction timescales dramatically alter synchronization properties. The network becomes birhythmic-it chooses between the in-phase and antiphase synchronization. Thus, the type of synchronization is not characteristic for the network structure. However, we conclude that the specific scenario of emergence and stabilization of synchronous solutions is much more characteristic.

Timing of sleep and its relationship with the endogenous melatonin rhythm

While much research has investigated the effects of exogenous melatonin on sleep, less is known about the relationship between the timing of the endogenous melatonin rhythm and the sleep-wake cycle. Significant inter-individual variability in the phase relationship between sleep and melatonin rhythms has been reported although the extent to which the variability reflects intrinsic and/or environmental differences is unknown. We examined the effects of different sleeping schedules on the time of dim light melatonin onset (DLMO) in 28 young, healthy adults. Participants chose to maintain either an early (22:30-06:30 h) or a late (00:30-08:30 h) sleep schedule for at least 3 weeks prior to an overnight laboratory visit. Saliva samples were collected under dim light (<2 lux) and controlled posture conditions to determine salivary DLMO. The 2-h difference between groups in the enforced sleep-wake schedule was associated with a concomitant 1.75-h delay in DLMO. The mean phase relationship between sleep onset and DLMO remained constant (~2 h). The variance in DLMO time, however, was greater in the late group (range 4.5 h) compared to the early group (range 2.4 h) perhaps due to greater effect of environmental influences in delayed sleep types or greater intrinsic instability in their circadian system. The findings contribute to our understanding of individual differences in the human circadian clock and have important implications for the diagnosis and treatment of circadian rhythm sleep disorders, in particular if a greater normative range for phase angle of entrainment occurs in individuals with later sleep-wake schedules.

Effects of ramelteon on insomnia symptoms induced by rapid, eastward travel

OBJECTIVE

Ramelteon, an MT(1)/MT(2) melatonin receptor agonist, was evaluated for its ability to reduce sleep-onset difficulties associated with eastward jet travel.

METHODS

Healthy adults (n=110) with a history of jet lag sleep disturbances were flown eastward across five time zones from Hawaii to the east coast of the US. Ramelteon 1, 4, or 8 mg or placebo was administered 5 min before bedtime (local time) for four nights. Sleep parameters were measured using polysomnography (PSG) on Nights 2, 3, and 4. Next-day residual effects were assessed using psychomotor and memory function tests.

RESULTS

Compared to placebo, there was a significant decrease in mean latency to persistent sleep (LPS) on Nights 2-4 with ramelteon 1mg (-10.64 min, P=0.030). No consistent significant differences were observed with ramelteon vs. placebo on measures of next-day residual effects except on Day 4 where participants in all ramelteon groups performed significantly worse on the immediate memory recall test compared with placebo (P < or = 0.05). The incidence of adverse events was similar for ramelteon and placebo.

CONCLUSION

After a 5-h phase advance due to eastward jet travel, ramelteon 1mg taken before bedtime for four nights reduced mean LPS relative to placebo in healthy adults.

Protein phosphatase PHLPP1 controls the light-induced resetting of the circadian clock

The pleckstrin homology domain leucine-rich repeat protein phosphatase 1 (PHLPP1) differentially attenuates Akt, PKC, and ERK1/2 signaling, thereby controlling the duration and amplitude of responses evoked by these kinases. PHLPP1 is expressed in the mammalian central clock, the suprachiasmatic nucleus, where it oscillates in a circadian fashion. To explore the role of PHLPP1 in vivo, we have generated mice with a targeted deletion of the PHLPP1 gene. Here we show that PHLPP1-null mice, although displaying normal circadian rhythmicity, have a drastically impaired capacity to stabilize the circadian period after light-induced resetting, producing a large phase shift after light resetting. Our findings reveal that PHLPP1 exerts a previously unappreciated role in circadian control, governing the consolidation of circadian periodicity after resetting.

Sleep and metabolism: an overview

Sleep and its disorders are increasingly becoming important in our sleep deprived society. Sleep is intricately connected to various hormonal and metabolic processes in the body and is important in maintaining metabolic homeostasis. Research shows that sleep deprivation and sleep disorders may have profound metabolic and cardiovascular implications. Sleep deprivation, sleep disordered breathing, and circadian misalignment are believed to cause metabolic dysregulation through myriad pathways involving sympathetic overstimulation, hormonal imbalance, and subclinical inflammation. This paper reviews sleep and metabolism, and how sleep deprivation and sleep disorders may be altering human metabolism.