Daytime naps in darkness phase shift the human circadian rhythms of melatonin and thyrotropin secretion

2000 ◽  
Vol 278 (2) ◽  
pp. R373-R382 ◽  
Author(s):  
Orfeu M. Buxton ◽  
Mireille L'Hermite-Balériaux ◽  
Fred W. Turek ◽  
Eve van Cauter
Keyword(s):  
Circadian Rhythms ◽  
Phase Shift ◽  
Light Exposure ◽  
Caloric Intake ◽  
Stimulus Exposure ◽  
Blood Samples ◽  
Circadian Misalignment ◽  
Circadian Phase ◽  
Before And After ◽  
Dim Light

To systematically determine the effects of daytime exposure to sleep in darkness on human circadian phase, four groups of subjects participated in 4-day studies involving either no nap (control), a morning nap (0900–1500), an afternoon nap (1400–2000), or an evening nap (1900–0100) in darkness. Except during the scheduled sleep/dark periods, subjects remained awake under constant conditions, i.e., constant dim light exposure (36 lx), recumbence, and caloric intake. Blood samples were collected at 20-min intervals for 64 h to determine the onsets of nocturnal melatonin and thyrotropin secretion as markers of circadian phase before and after stimulus exposure. Sleep was polygraphically recorded. Exposure to sleep and darkness in the morning resulted in phase delays, whereas exposure in the evening resulted in phase advances relative to controls. Afternoon naps did not change circadian phase. These findings indicate that human circadian phase is dependent on the timing of darkness and/or sleep exposure and that strategies to treat circadian misalignment should consider not only the timing and intensity of light, but also the timing of darkness and/or sleep.

156 Evening Light-Induced Circadian Phase Shift in Preschool-Aged Children

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A63-A64
Author(s):  
Lauren Hartstein ◽  
Lameese Akacem ◽  
Cecilia Diniz Behn ◽  
Shelby Stowe ◽  
Kenneth Wright ◽  
...  
Keyword(s):  
Phase Shift ◽  
Light Exposure ◽  
Light Stimulus ◽  
Phase Delay ◽  
Healthy Children ◽  
Dependent Manner ◽  
Circadian Phase ◽  
Light Intensities ◽  
Dim Light ◽  
Dose Dependent

Abstract Introduction In adults, exposure to light at night delays the timing of the circadian clock in a dose-dependent manner with intensity. Although children’s melatonin levels are highly suppressed by evening bright light, the sensitivity of young children’s circadian timing to evening light is unknown. This research aimed to establish an illuminance response curve for phase delay in preschool children as a result of exposure to varying light intensities in the hour before bedtime. Methods Healthy children (n=36, 3.0 – 4.9 years, 39% males), participated in a 10-day protocol. For 7 days, children followed a strict parent-selected sleep schedule. On Days 8-10, an in-home dim-light assessment was performed. On Day 8, dim light melatonin onset (DLMO) was measured through saliva samples collected in 20-30-min intervals throughout the evening until 1-h past habitual bedtime. On Day 9, children were exposed to a white light stimulus (semi-randomly assigned from 5lx to 5000lx) for 1-h before their habitual bedtime, and saliva was collected before, during, and after the exposure. On Day 10, children provided saliva samples in the evening for 2.5-h past bedtime for a final DLMO assessment. Phase angle of entrainment (habitual bedtime – DLMObaseline) and circadian phase delay (DLMOfinal – DLMObaseline) were computed. Results Final DLMO (Day 10) shifted between -8 and 123 minutes (M = 56.1 +/- 33.6 min; negative value = phase advance, positive value = phase delay) compared with DLMO at baseline (Day 8). Raw phase shift did not demonstrate a dose-dependent relationship with light intensity. Rather, we observed a robust phase delay across all intensities. Conclusion These data suggest preschoolers’ circadian clocks are immensely sensitive to a large range of light intensities, which may be mechanistically influenced by less mature ophthalmologic features (e.g. clearer lenses, larger pupils). With young children’s ever-growing use of light-emitting devices and evening exposure to artificial lighting, as well as the prevalence of behavioral sleep problems, these findings may inform recommendations for parents on the effects of evening light exposure on sleep timing in early childhood. Support (if any) This research was supported with funds from the Eunice Kennedy Shriver National Institute of Child Health & Human Development (R01-HD087707).

Late-night presentation of an auditory stimulus phase delays human circadian rhythms

2005 ◽  
Vol 289 (1) ◽  
pp. R209-R216 ◽  
Author(s):  
Namni Goel
Keyword(s):  
Circadian Rhythms ◽  
Auditory Stimulus ◽  
Core Body Temperature ◽  
Biological Clock ◽  
Phase Changes ◽  
Circadian Phase ◽  
Late Night ◽  
Human Circadian Rhythms ◽  
Before And After ◽  
Dim Light

Although light is considered the primary entrainer of circadian rhythms in humans, nonphotic stimuli, including exercise and melatonin also phase shift the biological clock. Furthermore, in birds and nonhuman mammals, auditory stimuli are effective zeitgebers. This study investigated whether a nonphotic auditory stimulus phase shifts human circadian rhythms. Ten subjects (5 men and 5 women, ages 18–72, mean age ± SD, 44.7 ± 21.4 yr) completed two 4-day laboratory sessions in constant dim light (<20 lux). They received two consecutive presentations of either a 2-h auditory or control stimulus from 0100 to 0300 on the second and third nights (presentation order of the stimulus and control was counterbalanced). Core body temperature (CBT) was collected and stored in 2-min bins throughout the study and salivary melatonin was obtained every 30 min from 1900 to 2330 on the baseline and poststimulus/postcontrol nights. Circadian phase of dim light melatonin onset (DLMO) and of CBT minimum, before and after auditory or control presentation was assessed. The auditory stimulus produced significantly larger phase delays of the circadian melatonin (mean ± SD, −0.89 ± 0.40 h vs. −0.27 ± 0.16 h) and CBT (−1.16 ± 0.69 h vs. −0.44 ± 0.27 h) rhythms than the control. Phase changes for the two circadian rhythms also positively correlated, indicating direct effects on the biological clock. In addition, the auditory stimulus significantly decreased fatigue compared with the control. This study is the first demonstration of an auditory stimulus phase-shifting circadian rhythms in humans, with shifts similar in size and direction to those of other nonphotic stimuli presented during the early subjective night. This novel stimulus may be a useful countermeasure to facilitate circadian adaptation after transmeridian travel or shift work.

Daily exercise facilitates phase delays of circadian melatonin rhythm in very dim light

2004 ◽  
Vol 286 (6) ◽  
pp. R1077-R1084 ◽  
Author(s):  
Laura K. Barger ◽  
Kenneth P. Wright ◽  
Rod J. Hughes ◽  
Charles A. Czeisler
Keyword(s):  
Exercise Intervention ◽  
Light Exposure ◽  
Phase Relationship ◽  
Shift Workers ◽  
Circadian Phase ◽  
Daily Exercise ◽  
Timing System ◽  
Before And After ◽  
Circadian Timing System ◽  
Dim Light

Shift workers and transmeridian travelers are exposed to abnormal work-rest cycles, inducing a change in the phase relationship between the sleep-wake cycle and the endogenous circadian timing system. Misalignment of circadian phase is associated with sleep disruption and deterioration of alertness and cognitive performance. Exercise has been investigated as a behavioral countermeasure to facilitate circadian adaptation. In contrast to previous studies where results might have been confounded by ambient light exposure, this investigation was conducted under strictly controlled very dim light (standing ∼0.65 lux; angle of gaze) conditions to minimize the phase-resetting effects of light. Eighteen young, fit males completed a 15-day randomized clinical trial in which circadian phase was measured in a constant routine before and after exposure to a week of nightly bouts of exercise or a nonexercise control condition after a 9-h delay in the sleep-wake schedule. Plasma samples collected every 30–60 min were analyzed for melatonin to determine circadian phase. Subjects who completed three 45-min bouts of cycle ergometry each night showed a significantly greater shift in the dim light melatonin onset (DLMO25%), dim light melatonin offset, and midpoint of the melatonin profile compared with nonexercising controls (Student t-test; P < 0.05). The magnitude of phase delay induced by the exercise intervention was significantly dependent on the relative timing of the exercise after the preintervention DLMO25% ( r = −0.73, P < 0.05) such that the closer to the DLMO25%, the greater the phase shift. These data suggest that exercise may help to facilitate circadian adaptation to schedules requiring a delay in the sleep-wake cycle.

An arousing, musically enhanced bird song stimulus mediates circadian rhythm phase advances in dim light

2006 ◽  
Vol 291 (3) ◽  
pp. R822-R827 ◽  
Author(s):  
Namni Goel
Keyword(s):  
Circadian Rhythms ◽  
Core Body Temperature ◽  
Bird Song ◽  
Circadian Phase ◽  
Mediated Effects ◽  
Subjective Night ◽  
Total Mood Disturbance ◽  
Before And After ◽  
Dim Light ◽  
Core Body

A musically enhanced bird song stimulus presented in the early subjective night phase delays human circadian rhythms. This study determined the phase-shifting effects of the same stimulus in the early subjective day. Eleven subjects (ages 18–63 yr; mean ± SD: 28.0 ± 16.6 yr) completed two 4-day laboratory sessions in constant dim light (<20 lux). They received two consecutive presentations of either a 2-h musically enhanced bird song or control stimulus from 0600 to 0800 on the second and third mornings while awake. The 4-day sessions employing either the stimulus or control were counterbalanced. Core body temperature (CBT) was collected throughout the study, and salivary melatonin was obtained every 30 min from 1900 to 2330 on the baseline and poststimulus/postcontrol nights. Dim light melatonin onset and CBT minimum circadian phase before and after stimulus or control presentation was assessed. The musically enhanced bird song stimulus produced significantly larger phase advances of the circadian melatonin (mean ± SD: 0.87 ± 0.36 vs. 0.24 ± 0.22 h) and CBT (1.08 ± 0.50 vs. 0.43 ± 0.37 h) rhythms than the control. The stimulus also decreased fatigue and total mood disturbance, suggesting arousing effects. This study shows that a musically enhanced bird song stimulus presented during the early subjective day phase advances circadian rhythms. However, it remains unclear whether the phase shifts are due directly to effects of the stimulus on the clock or are arousal- or dim light-mediated effects. This nonphotic stimulus mediates circadian resynchronization in either the phase advance or delay direction.

Circadian phase-shifting effects of nocturnal exercise in older compared with young adults

2003 ◽  
Vol 284 (6) ◽  
pp. R1542-R1550 ◽  
Author(s):  
Erin K. Baehr ◽  
Charmane I. Eastman ◽  
William Revelle ◽  
Susan H. Losee Olson ◽  
Lisa F. Wolfe ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Circadian Rhythms ◽  
Phase Shift ◽  
Sleep Time ◽  
Time Of Day ◽  
Phase Shifting ◽  
Circadian Phase ◽  
Dim Light ◽  
The Right

Exercise can phase shift the circadian rhythms of young adults if performed at the right time of day. Similar research has not been done in older adults. This study examined the circadian phase-delaying effects of a single 3-h bout of low-intensity nocturnal exercise in older ( n = 8; 55–73 yr old) vs. young ( n = 8; 20–32 yr old) adults. The exercise occurred at the beginning of each subject's habitual sleep time, and subjects sat in a chair in dim light during the corresponding time in the control condition. The dim-light melatonin onset (DLMO) was used as the circadian phase marker. The DLMO phase delayed more after the exercise than after the control condition. On average, the difference in phase shift between the exercise and control conditions was similar for older and young subjects, demonstrating that the phase-shifting effects of exercise on the circadian system are preserved in older adults. Therefore, exercise may potentially be a useful treatment to help adjust circadian rhythms in older and young adults.

scholarly journals Integration of brief light flashes varying in intensity and duration by the human circadian system

2019 ◽  
Author(s):  
Daniel S. Joyce ◽  
Manuel Spitschan ◽  
Jamie M. Zeitzer
Keyword(s):  
Phase Shift ◽  
Light Exposure ◽  
Temporal Integration ◽  
Circadian System ◽  
Flash Intensity ◽  
Flash Duration ◽  
Variable Intensity ◽  
Circadian Phase ◽  
Variable Duration ◽  
Circadian Phase Shift

AbstractThe human circadian system is exquisitely sensitive to light, through a pathway connecting the melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs) to the hypothalamic suprachiasmatic nuclei (SCN). ipRGCs are characterised by a delayed off-time following cessation of light exposure; we exploited this unusual physiologic property and examined how a sequence of flashes of bright light differing in intensity or duration presented in the biological night could delay the human circadian clock in vivo in healthy young participants (n=54). To understand the mechanism underlying circadian photoreception, we probed temporal integration by manipulating flash intensity and duration independently. In a 34-hour in-laboratory between-subjects design, we examined variable-intensity (3, 30, 95, 300, 950, 3000, or 9500 photopic lux; n=28 participants) flashes at fixed duration (2 ms), and variable-duration (10 μs, 100 μs, 1 ms, 10 ms, 100 ms, 1 sec, 10 sec) flashes at fixed intensity (2000 photopic lux; n=31 participants). We measured the phase shift of dim-light melatonin onset on the subsequent evening, and acute melatonin suppression and alertness during the flash sequence. In the variable-intensity study, we find a clear sigmoidal dose-response relationship for flash intensity and the induced circadian phase shift. In the variable-duration study, we find no parametric relationship between flash duration and induced circadian phase shift, indicating a relative insensitivity of the circadian system to flashes varying in duration. As the intermittent periods of darkness in our stimulation paradigm supports the recovery of extrinsic rod-cone signalling into the ipRGCs, our results strongly suggest rod-cone contributions into circadian photoreception.

scholarly journals Distinct Circadian Assessments From Wearable Data Reveal Social Distancing Promoted Internal Desynchrony Between Circadian Markers

2021 ◽  
Vol 3 ◽  
Author(s):  
Yitong Huang ◽  
Caleb Mayer ◽  
Olivia J. Walch ◽  
Clark Bowman ◽  
Srijan Sen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Circadian Rhythms ◽  
Phase Error ◽  
Laboratory Data ◽  
The Body ◽  
Social Distancing ◽  
Circadian Phase ◽  
The Social ◽  
Before And After ◽  
Using Data

Mobile measures of human circadian rhythms (CR) are needed in the age of chronotherapy. Two wearable measures of CR have recently been validated: one that uses heart rate to extract circadian rhythms that originate in the sinoatrial node of the heart, and another that uses activity to predict the laboratory gold standard and central circadian pacemaker marker, dim light melatonin onset (DLMO). We first find that the heart rate markers of normal real-world individuals align with laboratory DLMO measurements when we account for heart rate phase error. Next, we expand upon previous work that has examined sleep patterns or chronotypes during the COVID-19 lockdown by studying the effects of social distancing on circadian rhythms. In particular, using data collected from the Social Rhythms app, a mobile application where individuals upload their wearable data and receive reports on their circadian rhythms, we compared the two circadian phase estimates before and after social distancing. Interestingly, we found that the lockdown had different effects on the two ambulatory measurements. Before the lockdown, the two measures aligned, as predicted by laboratory data. After the lockdown, when circadian timekeeping signals were blunted, these measures diverged in 70% of subjects (with circadian rhythms in heart rate, or CRHR, becoming delayed). Thus, while either approach can measure circadian rhythms, both are needed to understand internal desynchrony. We also argue that interventions may be needed in future lockdowns to better align separate circadian rhythms in the body.

scholarly journals Characterizing the modern light environment and its influence on circadian rhythms

2021 ◽  
Vol 288 (1955) ◽  
pp. 20210721
Author(s):  
Dennis Khodasevich ◽  
Susan Tsui ◽  
Darwin Keung ◽  
Debra J. Skene ◽  
Victoria Revell ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Light Exposure ◽  
Circadian Disruption ◽  
Light Sources ◽  
Night Time ◽  
Circadian Phase ◽  
Temperature Rhythm ◽  
Four Seasons ◽  
Significant Difference ◽  
The Impact

Humans have largely supplanted natural light cycles with a variety of electric light sources and schedules misaligned with day-night cycles. Circadian disruption has been linked to a number of disease processes, but the extent of circadian disruption among the population is unknown. In this study, we measured light exposure and wrist temperature among residents of an urban area during each of the four seasons, as well as light illuminance in nearby outdoor locations. Daily light exposure was significantly lower for individuals, compared to outdoor light sensors, across all four seasons. There was also little seasonal variation in the realized photoperiod experienced by individuals, with the only significant difference occurring between winter and summer. We tested the hypothesis that differential light exposure impacts circadian phase timing, detected via the wrist temperature rhythm. To determine the influence of light exposure on circadian rhythms, we modelled the impact of morning and night-time light exposure on the timing of the maximum wrist temperature. We found that morning and night-time light exposure had significant but opposing impacts on maximum wrist temperature timing. Our results demonstrate that, within the range of exposure seen in everyday life, night-time light can delay the onset of the maximum wrist temperature, while morning light can lead to earlier onset. Our results demonstrate that humans are minimizing natural seasonal differences in light exposure, and that circadian shifts and disruptions may be a more regular occurrence in the general population than is currently recognized.

scholarly journals The Effect of Cognitive Behaviour Therapy on Sleep and Circadian Rhythm in Young College Students

2021 ◽  
pp. 43-47
Author(s):  
Shweta Kanchan ◽  
Sunita Tiwari ◽  
Shweta Singh
Keyword(s):  
Cognitive Behaviour Therapy ◽  
Sleep Time ◽  
Behaviour Therapy ◽  
Circadian Phase ◽  
Dim Light Melatonin Onset ◽  
College Going ◽  
Cognitive Behaviour ◽  
Before And After ◽  
Sleep Parameters ◽  
Dim Light

The present study is to study the effect of cognitive behaviour therapy on various sleep parameters and circadian phase rhythmic in young college going adults. Fifty young college going adults were chosen from the MBBS and BDS students of King George's Medical University Lucknow, their polysomnography was conducted along with it salivary melatonin estimation was conducted to find the time of Dim light melatonin onset (DLMO), the subjects were administered cognitive behaviour therapy (CBT),after completing the sessions of cognitive behaviour therapy another Polysomnographic study and DLMO estimation was conducted, various sleep parameters were compared before and after the CBT. The study showed an improvement in the steep quality, a decrease in daytime sleepiness along with this total sleep time significantly increased, sleep efficiency also improved and there was a decrease in the REM sleep latency. The Dim light melatonin onset advanced for the subjects and the chronotype showed an inclination towards an earlier timings.

scholarly journals Effects of Circadian Phase Tailored Light Therapy on Sleep, Mood, and Cognition in Alzheimer’s Disease: Preliminary Findings in a Pivotal Study

2022 ◽  
Vol 12 ◽  
Author(s):  
Riccardo Cremascoli ◽  
Davide Sparasci ◽  
Gianluca Giusti ◽  
Stefania Cattaldo ◽  
Elisa Prina ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Circadian Rhythms ◽  
Sleep Quality ◽  
Cognitive Functioning ◽  
Light Exposure ◽  
Light Therapy ◽  
Circadian Phase ◽  
Falling Asleep ◽  
Mood And Cognition

It is shown that the circadian system is affected in patients with Alzheimer’s disease (AD) even at an early stage of the disease and that such dysfunction may be detrimental to sleep, mood, and cognitive functioning. Light is a strong central modulator of the circadian rhythms and is potentially beneficial to mood and cognitive functioning via a direct effect or indirectly via its modulating effects on circadian rhythms. This study focuses on tracking the effect of light therapy on sleep quality, mood, and cognition in AD of mild/moderate severity. We performed a single-blind randomized controlled trial to investigate the effects of a light therapy treatment tailored to the individual circadian phase as measured by dim light melatonin onset (DLMO). Such a treatment induced an objective circadian phase shift consistent with the melatonin phase response curve to light exposure, led to a shortening of the phase angle DLMO-falling asleep time, and was associated with an improvement in subjective sleep quality and cognitive performance.

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