CamNtech Research Library


CamNtech products have been trusted by specialist researchers for 25 years. Our research library contains peer reviewed publications citing the use of our devices. Filter by product, application, keyword, author or use free text search to locate your area of interest.

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Found 48 Results

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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; […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

Publication Date: December 10, 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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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, […]

Related Product: MotionWatch

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) […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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

See link

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

Endogenous modulation of human visual cortex activity improves perception at twilight

Perception, particularly in the visual domain, is drastically influenced by rhythmic changes in ambient lighting conditions. Anticipation of daylight changes by the circadian system is critical for survival. However, the neural bases of time-of-day-dependent modulation in human perception are not yet understood. We used fMRI to study brain dynamics during resting-state and close-to-threshold visual perception […]

Related Product: Actiwatch Mini

Publication Date: April 10, 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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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 […]

Related Product: MotionWatch

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

Disruption of The Presumed Circadian Sleep Maintenance Zone Predicts Cognitive Impairment in Older Adults.

Background Age-related changes in sleep quality are associated with cognitive impairment in older adults and may play a role in the trajectory of cognitive decline in Alzheimer’s disease. Circadian dysregulation of the sleep maintenance zone could in part explain these changes in sleep quality and might be associated with cognitive impairment observed in older adults. […]

Related Product: MotionWatch

Publication Date: July 12, 2016

The investigation of chronobiological aspects of non-visual effects of light in humans.

The chronobiological studies on non-visual lighting effects presented in this postdoctoral thesis show qualitative differences of the same depending on age, long- and short-term adaptation. Chromatic pupillometry was also used to examine the extent to which the pupil reflex on light is suitable for use as a marker for melanopsin-dependent functions in healthy people and […]

Related Product: MotionWatch

Publication Date: January 25, 2016

Circadian sleep/wake rhythm abnormalities as a risk factor of a poststroke apathy

Background Poststroke apathy affects 19–55% of patients following stroke and has a negative impact on functional recovery, general health, and quality of life, as well as being a source of significant burden for caregivers. Aims A major clinical issue is the delayed diagnosis of post-stroke apathy, and so the aim of our study is to […]

Related Product: MotionWatch

Publication Date: July 1, 2015

Ring the bell for Matins: circadian adaptation to split sleep by cloistered monks and nuns

Cloistered monks and nuns adhere to a 10-century-old strict schedule with a common zeitgeber of a night split by a 2- to 3-h-long Office (Matins). The authors evaluated how the circadian core body temperature rhythm and sleep adapt in cloistered monks and nuns in two monasteries. Five monks and five nuns following the split-sleep night […]

Related Product: Actiwatch Mini

Publication Date: November 14, 2011

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