Publications
CamNtech Research Library
CamNtech products have been trusted by specialist researchers for over 25 years.
Our research library contains peer reviewed publications citing the use of our devices.
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Can actigraphy be used to define lithium response dimensions in bipolar disorders?
Background: Actigraphy is commonly used in case-control studies to explore sleep-wake patterns and circadian rhythmicity in bipolar disorders (BD). However, there is limited ecological research regarding actigraphy parameters associated with response to lithium (Li_Resp). Methods: Outpatients with BD-I (n=70) and BD-II (n=20) who were all prescribed prophylactic Li undertook 21 consecutive days of actigraphy recording. […]
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Publication Date: February 2, 2021
A brief report of sleep and circadian rhythm quotas in a population of dog owners in North Carolina USA
Objectives To characterize sleep and circadian rhythms of a sample population of healthy, dog-owning adults from North Carolina, USA. Methods Actigraphy was used to analyze sleep-wake patterns in forty-two dog owners from the Raleigh area in North Carolina. Sleep quotas, including sleep duration, efficiency, and fragmentation were measured alongside a Non-parametric Circadian Rhythms Analysis (NPCRA) […]
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Publication Date: January 22, 2021
Sleep, Circadian Rhythmicity and Response to Chronotherapy in University Students: Tips from Chronobiology Practicals
Chronobiology is not routinely taught to biology or medical students in most European countries. Here we present the results of the chronobiology practicals of a group of students of the University of Padova, with a view to highlight some interesting features of this group, and to share a potentially interesting cross-faculty teaching experience. Thirty-eight students […]
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Publication Date: January 21, 2021
Circadian Patterns of Patients with Type 2 Diabetes and Obstructive Sleep Apnea
Sleep apnea, a condition that modifies sleep and circadian rhythms, is highly prevalent in patients with diabetes. However, it is not known if there is an association between sleep apnea, circadian alterations and glycemic regulation in this type of patient. Here, a polysomnographic study was carried out on 21 women and 25 men (mean age […]
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Publication Date: January 11, 2021
Sleep− wake cycle dysregulation in idiopathic REM sleep behaviour disorder
Alteration of the circadian sleep−wake rhythm has been suggested in patients affected by idiopathic rapid eye movement sleep behaviour disorder. Because actigraphy is the validated instrument to monitor the sleep−wake cycle, the aim of the present study was to investigate the circadian sleep−wake rhythm in patients with idiopathic rapid eye movement sleep behaviour disorder compared […]
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Publication Date: December 1, 2020
Effect of vestibular stimulation using a rotatory chair in human rest/activity rhythm
The vestibular system is responsible for sensing every angular and linear head acceleration, mainly during periods of motor activity. Previous animal and human experiments have shown biological rhythm disruptions in small rodents exposed to a hypergravity environment, but also in patients with bilateral vestibular loss compared to a control population. This raised the hypothesis of […]
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Publication Date: September 26, 2020
Timed physical exercise does not influence circadian rhythms and glucose tolerance in rotating night shift workers: The EuRhythDia study
Objectives: Night shift workers are at cardiometabolic risk due to circadian misalignment. We investigated whether infrequent exercise before each night shift that intentionally would not improve physical performance improves glucose tolerance and 24-h blood pressure profiles and synchronizes circadian rhythms of melatonin and cortisol in rotating night shift workers. Methods: A total of 24 rotating […]
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Publication Date: September 25, 2020
Prediction of individual differences in circadian adaptation to night work among older adults: application of a mathematical model using individual sleep-wake and light exposure data
Circadian misalignment remains a distinct challenge for night shift workers. Variability in individual sleep-wake/light-dark patterns might contribute to individual differences in circadian alignment in night shift workers. In this simulation study, we compared the predicted phase shift from a mathematical model of the effect of light on the human circadian pacemaker to the observed melatonin […]
Related Product: MotionWatch
Publication Date: September 6, 2020
Disturbances of Continuous Sleep and Circadian Rhythms Account for Behavioral Difficulties in Children with Autism Spectrum Disorder
Sleep disorders are among the most common comorbidities in children with Autism Spectrum Disorder (ASD), and subjectively defined sleep disturbances have been related to ASD symptom severity. However, no study has investigated the differential impact of objectively measured sleep and circadian rhythm disturbances on behavioral difficulties in this population. Fifty-two children with ASD aged 3–10 […]
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Publication Date: June 24, 2020
Rest-activity rhythm in breast cancer survivors: an update based on non-parametric indices
Recently we evaluated by actigraphy the rest-activity circadian rhythm (RAR) in breast cancer (BC) survivors at 5 years from primary diagnosis, as well as in a control group with similar age and body mass index (BMI). RAR, analyzed by Cosinor method, resulted significantly different in BC survivors compared to healthy subjects: BC survivors showed lower […]
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Publication Date: April 24, 2020
Sleep-Wake Cycle in Alzheimer’s Disease Is Associated with Tau Pathology and Orexin Dysregulation
Background:Alzheimer’s disease (AD) is the most common form of dementia. It is mainly characterized by a progressive deterioration of cognition, but sleep-wake cycle disturbances frequently occur. Irregular sleep-wake cycle, insomnia, and daytime napping usually occur in patients with AD in the course of the disease. Objective:The aim of the present study was to verify the […]
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Publication Date: February 10, 2020
Disruption in daily eating-fasting and activity-rest cycles in Indian adolescents attending school.
A lifestyle with erratic eating patterns and habits predisposes youngsters to obesity. Through a two-phase feasibility study among Indian students living in the Delhi area, we longitudinally examined the following: (1) the daily eating-fasting cycles of students (N = 34) in school and college using smartphones as they transition from high school (aged 13–15 years; […]
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Publication Date: January 10, 2020
Pupillometry evaluation of melanopsin retinal ganglion cell function and sleep-wake activity in pre-symptomatic Alzheimer’s disease
Background Melanopsin-expressing retinal ganglion cells (mRGCs), intrinsically photosensitive RGCs, mediate the light-based pupil response and the light entrainment of the body’s circadian rhythms through their connection to the pretectal nucleus and hypothalamus, respectively. Increased awareness of circadian rhythm dysfunction in neurological conditions including Alzheimer’s disease (AD), has led to a wave of research focusing on […]
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Publication Date: December 10, 2019
Summer-winter difference in 24-h melatonin rhythms in subjects on a 5-workdays schedule in Siberia without daylight saving time transitions
The study aimed to quantify a seasonal change in circadian rhythms and its relationship to the social/sleep regimen in humans living in Novosibirsk (55°N), using the naturalistic situation that daylight saving time transitions have been abolished in Russia. Sixty-three volunteers entered the study, and 46 completed it. One group got up at ~6 a.m. and […]
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Publication Date: December 1, 2019
Smart Rehabilitation for Neuro-Disability: A Review
Neurological disorders are increasing globally due to various factors such as change in lifestyle patterns as well as personal and professional stress. Scientists belonging to various research and development organizations from a variety of disciplines are working together to invent new rehabilitation devices. Emerging trends in electronics and information technology-enabled devices provide a platform for […]
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Publication Date: November 20, 2019
Sleep-wake disorders in Alzheimer’s disease: further genetic analyses in relation to objective sleep measures
This paper presents updated analyses on the genetic associations of sleep disruption in individuals with Alzheimer’s disease (AD). We published previously a study of the association between single nucleotide polymorphisms (SNPs) found in eight genes related to circadian rhythms and objective measures of sleep-wake disturbances in 124 individuals with AD. Here, we present new relevant […]
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Publication Date: November 19, 2019
The Effect of a Common Daily Schedule on Human Circadian Rhythms During the Polar Day in Svalbard: A Field Study
All Arctic visitors have to deal with extreme conditions, including a constant high light intensity during the summer season or constant darkness during winter. The light/dark cycle serves as the most potent synchronizing signal for the biological clock, and any Arctic visitor attending those regions during winter or summer would struggle with the absence of […]
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Publication Date: October 9, 2019
Variation near MTNR1A associates with early development and interacts with seasons
Melatonin is a circadian regulatory hormone with neuroprotective properties. We have previously demonstrated the association of the genetic variant rs12506228 near the melatonin receptor 1A gene (MTNR1A) with intolerance to shift‐work. Furthermore, this variant has been connected to Alzheimer’s disease. Because of the previously suggested role of melatonin signalling in foetal neurocognitive and sleep development, […]
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Publication Date: October 7, 2019
The Relationship between Fatigue and Actigraphy-Derived Sleep and Rest-Activity Patterns in Cancer Survivors
Study Objectives: To investigate objectively-measured sleep and rest-activity cycles in fatigued and non-fatigued cancer survivors. We hypothesized that sleep and rest-activity cycles would be more disturbed in people experiencing clinically-relevant cancer-related fatigue, and that objective measures of sleep would be associated with the severity of fatigue in cancer survivors. Methods: Cancer survivors (n = 87) […]
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Publication Date: September 6, 2019
A 6-day combined wake and light therapy trial for unipolar depression
Background There are a dozen studies on double or triple chronotherapy in depression (sleep deprivation [wake therapy] + light therapy + sleep advance/stabilization). We investigated efficacy and feasibility of a modified triple chronotherapy protocol. Methods Thirty-five hospitalized patients with moderately severe non-seasonal depressive disorder, mostly free from antidepressants, underwent a 6-day protocol consisting of partial sleep deprivation late in […]
Related Product: MotionWatch
Publication Date: August 19, 2019
Response to Treatment With Lemborexant: Subjects With Irregular Sleep-Wake Rhythm Disorder and Alzheimer’s Disease Dementia
Irregular sleep-wake rhythm disorder (ISWRD) is a circadian rhythm sleep disorder, distinct from insomnia, which is characterized by the irregular distribution of sleep bouts across the 24-hour period rather than consolidated sleep at night. ISWRD symptoms are common in patients with Alzheimer’s disease dementia (AD-D). Pathology of ISWRD includes disturbed circadian rhythmicity, neuronal loss in […]
Related Product: MotionWatch
Publication Date: July 14, 2019
Decreased need for sleep as an endophenotype of bipolar disorder: an actigraphy study
Reports of subjective sleep impairments have been replicated in adults with bipolar disorder (BD), young BD patients, and even children of parents with BD. Furthermore, circadian rhythm alterations are a core feature of BD. Despite the impairment in circadian rhythms and altered sleep included in various heuristic developmental models of BD, thus far, biomarkers have […]
Related Product: MotionWatch
Publication Date: July 1, 2019
Effects of a dawn-dusk simulation on circadian rest-activity cycles, sleep, mood and well-being in dementia patients
Light is the most powerful “zeitgeber” signal to synchronize circadian sleep-wake cycles. In dementia, these rhythms are often fragmented — probably due to loss of neuronal function of the suprachiasmatic nuclei (the biological “master clock” in the brain) and/or weakness of external zeitgebers. We investigated the effects of a prototype dawn-dusk simulator (DDS) on circadian […]
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Publication Date: June 25, 2019
Rest-activity circadian rhythm in breast cancer survivors at 5 years after the primary diagnosis
Rest-activity circadian rhythm (RAR) is a marker of the circadian timing system. Particular attention has been given to RAR characteristics in cancer diseases. Specifically, alterations of RAR parameters have been found, at different stages of clinical pathway, in breast cancer (BC) patients. No studies to date have analyzed RAR alterations in breast cancer survivors several […]
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Publication Date: June 10, 2019
Beyond the low frequency fluctuations morning and evening differences in human brain
Human performance, alertness, and most biological functions express rhythmic fluctuations across a 24-hour-period. This phenomenon is believed to originate from differences in both circadian and homeostatic sleep-wake regulatory processes. Interactions between these processes result in time-of-day modulations of behavioral performance as well as brain activity patterns. Although the basic mechanism of the 24-hour clock is […]
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Publication Date: June 6, 2019
Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime
Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial […]
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Publication Date: June 2, 2019
Pregnancy Induces an Earlier Chronotype in Both Mice and Women
Daily rhythms generated by endogenous circadian mechanisms and synchronized to the light-dark cycle have been implicated in the timing of birth in a wide variety of species. Although chronodisruption (e.g., shift work or clock gene mutations) is associated with poor reproductive outcomes, little is known about circadian timing during pregnancy. This study tested whether daily […]
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Publication Date: April 24, 2019
Hypothalamic‐pituitary‐adrenal axis differentially responses to morning and evening psychological stress in healthy subjects
Aim The hypothalamic‐pituitary‐adrenal (HPA) axis responds to changing environmental demands including psychological stressors. The aim of the present study was to assess whether the time of day effects on the acute response of HPA axis activity to acute psychological stress. Method We studied 27 healthy young subjects. The subjects were participated two experiments as follows. […]
Related Product: MotionWatch
Publication Date: March 3, 2019
Strategies to decrease social jetlag: Reducing evening blue light advances sleep and melatonin
The timing of sleep is under the control of the circadian clock, which uses light to entrain to the external light‐dark cycle. A combination of genetic, physiological and environmental factors produces individual differences in chronotype (entrained phase as manifest in sleep timing). A mismatch between circadian and societal (e.g., work) clocks leads to a condition […]
Related Product: MotionWatch
Publication Date: December 2, 2018
Impact of long-term daylight deprivation on retinal light sensitivity, circadian rhythms and sleep during the Antarctic winter.
Long-term daylight deprivation such as during the Antarctic winter has been shown to lead to delayed sleep timing and sleep fragmentation. We aimed at testing whether retinal sensitivity, sleep and circadian rest-activity will change during long-term daylight deprivation on two Antarctic bases (Concordia and Halley VI) in a total of 25 healthy crew members (mean […]
Related Product: MotionWatch
Publication Date: November 1, 2018
Suppression of salivary melatonin secretion under 100-Hz flickering and non-flickering blue light
Background Bright light at night is known to suppress melatonin secretion. Novel photoreceptors named intrinsically photosensitive retinal ganglion cells (ipRGCs) are mainly responsible for projecting dark/bright information to the suprachiasmatic nucleus and thus regulating the circadian system. However, it has been shown that the amplitude of the electroretinogram of ipRGCs is considerably lower under flickering […]
Related Product: MotionWatch
Publication Date: October 19, 2018
Does the moon influence sleep in small-scale societies?
Objectives The lunar cycle is expected to influence sleep-wake patterns in human populations that have greater exposure to the environment, as might be found in forager populations that experience few environmental buffers. We investigated this “moonlight” hypothesis in two African populations: one composed of hunter-gatherers (with minimal environmental buffering) and the other rural agriculturalists (with […]
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Publication Date: October 4, 2018
Sleep and neurobehavioral performance vary by work start time during non-traditional day shifts
Introduction It is established that shiftwork causes sleep loss and circadian misalignment. Individuals who work non-traditional day shifts that encroach into typical sleep times, such as those in the service and transportation sectors, may also experience sleep and circadian disruption. We aimed to determine how neurobehavioral performance and sleep would be affected by work start […]
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Publication Date: October 1, 2018
Daytime sleepiness, salivary cortisol and melatonin levels during four-week blue light blockade. Do we adapt?
Blue light (BL, short wavelength, ca. 480 nm) is known to influence circadian rhythm system, alertness, cognitive and affective functioning of humans (see e.g. Fisk et al., 2018). In this experiment we limited the BL exposure to approximately 10%, by providing the participants with amber contact lenses – to be used continuously during four weeks. […]
Related Product: MotionWatch
Publication Date: September 25, 2018
Buying time: a proof-of-concept randomized controlled trial to improve sleep quality and cognitive function among older adults with mild cognitive impairment
Current evidence suggests that good quality sleep is associated with preserved cognitive function and reduced dementia risk in older adults. Sleep complaints are especially common among older adults with mild cognitive impairment (MCI), and this may contribute to their increased risk for progression to dementia. Thus, improving their sleep may be important for maintaining their […]
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Publication Date: August 17, 2018
High-accuracy determination of internal circadian time from a single blood sample
BACKGROUND. The circadian clock is a fundamental and pervasive biological program that coordinates 24-hour rhythms in physiology, metabolism, and behavior, and it is essential to health. Whereas therapy adapted to time of day is increasingly reported to be highly successful, it needs to be personalized, since internal circadian time is different for each individual. In […]
Related Product: MotionWatch
Publication Date: June 28, 2018
Actimetric Day/Night Index as a Predictor of Treatment Response in Depression
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Related Product: MotionWatch
Publication Date: June 1, 2018
Examining courses of sleep quality and sleepiness in full 2 weeks on/2 weeks off offshore day shift rotations
To better understand sleep quality and sleepiness problems offshore, we examined courses of sleep quality and sleepiness in full 2-weeks on/2-weeks off offshore day shift rotations by comparing pre-offshore (1 week), offshore (2 weeks) and post-offshore (1 week) work periods. A longitudinal observational study was conducted among N=42 offshore workers. Sleep quality was measured subjectively […]
Related Product: MotionWatch
Publication Date: May 16, 2018
Investigating daily fatigue scores during two-week offshore day shifts
Objectives This study examined daily scores of fatigue and circadian rhythm markers over two-week offshore day shift periods. Methods A prospective cohort study among N = 60 offshore day-shift workers working two-week offshore shifts was conducted. Offshore day shifts lasted from 07:00 – 19:00 h. Fatigue was measured objectively with pre- and post-shift scores of […]
Related Product: MotionWatch
Publication Date: April 27, 2018
Can short-wavelength depleted bright light during single simulated night shifts prevent circadian phase shifts?
In single night shifts, extending habitual wake episodes leads to sleep deprivation induced decrements of performance during the shift and re-adaptation effects the next day. We investigated whether short-wavelength depleted (=filtered) bright light (FBL) during a simulated night shift would counteract such effects. Twenty-four participants underwent a simulated night shift in dim light (DL) and […]
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Publication Date: May 1, 2017
Daily light exposure patterns reveal phase and period of the human circadian clock
Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual’s daily light perception and intrinsic pacemaker period under free-running conditions. Establishing individual estimates of circadian phase and period can be time-consuming. We show that circadian phase can be […]
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Publication Date: April 28, 2017
Mechanisms of Non-photic Entrainment
This chapter reviews how non-photic cues like temperature, food, anxiety and induced activity lead to circadian rhythm entrainment in mammals. Generally speaking, when dealing with entrainment by different photic and non-photic zeitgebers, we are only able to show that a certain type of stimulus can or cannot entrain the circadian system, therefore, the comparison is […]
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Publication Date: February 16, 2017
Segmented sleep in a nonelectric, small‐scale agricultural society in Madagascar
Objectives We studied sleep in a rural population in Madagascar to (i) characterize sleep in an equatorial small-scale agricultural population without electricity, (ii) assess whether sleep is linked to noise levels in a dense population, and (iii) examine the effects of experimentally introduced artificial light on sleep timing. Methods Using actigraphy, sleep–wake patterns were analyzed […]
Related Product: MotionWatch
Publication Date: February 9, 2017
Activity/rest cycle and disturbances of structural backbone of cerebral networks in aging
Objective Although aging is associated with alterations of both activity/rest cycle and brain structure, few studies have evaluated associations between these processes. The aim of this study was to examine relationship between activity/rest cycle quality and brain structural integrity in aging subjects by exploring both grey and white matter compartments. Material and methods Fifty-eight elderly […]
Related Product: MotionWatch
Publication Date: February 1, 2017
Hadza sleep biology: Evidence for flexible sleep‐wake patterns in hunter‐gatherers.
Objectives Cross-cultural sleep research is critical to deciphering whether modern sleep expression is the product of recent selective pressures, or an example of evolutionary mismatch to ancestral sleep ecology. We worked with the Hadza, an equatorial, hunter-gatherer community in Tanzania, to better understand ancestral sleep patterns and to test hypotheses related to sleep segmentation. Methods […]
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Publication Date: January 7, 2017
Scheduled evening sleep and enhanced lighting improve adaptation to night shift work in older adults
Objectives We tested whether a sleep and circadian-based treatment shown to improve circadian adaptation to night shifts and attenuate negative effects on alertness, performance and sleep in young adults would also be effective in older adults. Methods We assessed subjective alertness, sustained attention (psychomotor vigilance task, PVT), sleep duration (actigraphy) and circadian timing (salivary dim-light […]
Related Product: MotionWatch
Publication Date: November 16, 2016
Validation of the Munich ChronoType Questionnaire against actigraphy
Munich ChronoType Questionnaire (MCTQ) is a relatively new self-report instrument to measure chronotype and social jetlag. Despite its increasing use in research, validation studies against objectively measured circadian rhythm are scarce. This study aimed to analyze associations of the MCTQ parameters with those of restactivity cycle (indicator of sleep-wake rhythm) delivered from accelerometry. It was […]
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Publication Date: October 14, 2016
The Relationship between Circadian Dysfunction and Cognitive Impairment in Individuals with Parkinson’s Disease
Parkinson’s Disease (PD) is a brain disorder associated with a variety of motor (e.g., rigidity, tremor) and nonmotor (e.g., cognitive impairment, sleep dysfunction) symptoms. Recent evidence suggests that PD patients may also have dysfunctional circadian rhythms: oscillators responsible for many behavioral and physiological functions (e.g., sleep-wake cycle, cognitive performance). No study to date has measured […]
Related Product: MotionWatch
Publication Date: September 5, 2016
O35-2 Current and cumulative night shift work and subclinical atherosclerosis–results of the gutenberg health study
Objectives Research on shift work and cardiovascular health is challenging because of the long follow-up time that is needed to cover late outcomes such as myocardial morbidity (e.g., myocardial infarction), or mortality. The aim of this cross-sectional analysis was to investigate associations and dose-response relationships between (1) current and (2) cumulative exposure to night shift […]
Related Product: MotionWatch
Publication Date: September 1, 2016
O35-4 Course of sleepiness and sleep parameters in 2-2 offshore rotations
Introduction Sleep and fatigue problems are among the most common health and safety concerns in the offshore oil and gas industry. To understand sleep and fatigue problems offshore, we examined the course of sleepiness and sleep parameters across 2-2 offshore rotations and compared pre-departure (1 week), offshore work (2 weeks) and recovery (1 week) periods. […]
Related Product: MotionWatch
Publication Date: September 1, 2016
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