Effects of Bright and Dim Light Intensities during Daytime upon Circadian Rhythm of Core Temperature in Man

1994 ◽  
pp. 285-289 ◽  
Author(s):  
H. Tokura ◽  
M. Yutani ◽  
T. Morita ◽  
M. Murakami
Keyword(s):  
Circadian Rhythm ◽  
Core Temperature ◽  
Light Intensities ◽  
Dim Light

scholarly journals Thresholds and noise limitations of colour vision in dim light

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160065 ◽  
Author(s):  
Almut Kelber ◽  
Carola Yovanovich ◽  
Peter Olsson
Keyword(s):  
Shot Noise ◽  
Colour Vision ◽  
Absolute Threshold ◽  
Colour Discrimination ◽  
Dark Noise ◽  
Visual Threshold ◽  
Light Intensities ◽  
Purkinje Shift ◽  
Dim Light ◽  
Receptor Noise

Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift. Rod–cone interactions have not been shown to improve colour vision in dim light, but may contribute to colour vision in mesopic light intensities. Frogs and toads that have two types of rods use opponent signals from these rods to control phototaxis even at their visual threshold. However, for tasks such as prey or mate choice, their colour discrimination abilities fail at brighter light intensities, similar to other vertebrates, probably limited by the dark noise in cones. This article is part of the themed issue 'Vision in dim light’.

Core temperature circadian rhythm across aging in Spontaneously Hypertensive Rats

2021 ◽  
Vol 97 ◽  
pp. 102807
Author(s):  
Leonardo M.T. de Rezende ◽  
Leandro C. Brito ◽  
Anselmo G. Moura ◽  
Alexandre J.L.D. Costa ◽  
Tiago F. Leal ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Core Temperature ◽  
Spontaneously Hypertensive Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive

Circadian rhythm changes in core temperature over the menstrual cycle: method for noninvasive monitoring

2000 ◽  
Vol 279 (4) ◽  
pp. R1316-R1320 ◽  
Author(s):  
Mary D. Coyne ◽  
Christina M. Kesick ◽  
Tammy J. Doherty ◽  
Margaret A. Kolka ◽  
Lou A. Stephenson
Keyword(s):  
Circadian Rhythm ◽  
Menstrual Cycle ◽  
Core Temperature ◽  
Temperature Sensor ◽  
Temperature Sensors ◽  
Cycle Phase ◽  
Noninvasive Method ◽  
Menstrual Cycle Phase ◽  
Cosinor Analysis ◽  
Temperature Amplitude

The purpose of this study was to determine whether core temperature (Tc) telemetry could be used in ambulatory women to track changes in the circadian Tc rhythm during different phases of the menstrual cycle and, more specifically, to detect impending ovulation. Tcwas measured in four women who ingested a series of disposable temperature sensors. Data were collected each minute for 2–7 days and analyzed in 36-h segments by automated cosinor analysis to determine the mesor (mean temperature), amplitude, period, acrophase (time of peak temperature), and predicted circadian minimum core temperature (Tc-min) for each cycle. The Tcmesor was higher ( P ≤ 0.001) in the luteal (L) phase (37.39 ±0.13°C) and lower in the preovulatory (P) phase (36.91 ±0.11°C) compared with the follicular (F) phase (37.08 ±0.13°C). The predicted Tc-min was also greater in L (37.06 ± 0.14°C) than in menses (M; 36.69 ± 0.13°C), F (36.6 ± 0.16°C), and P (36.38 ± 0.08°C) ( P ≤ 0.0001). During P, the predicted Tc-min was significantly decreased compared with M and F ( P ≤ 0.0001). The amplitude of the Tc rhythm was significantly reduced in L compared with all other phases ( P ≤ 0.005). Neither the period nor acrophase was affected by menstrual cycle phase in ambulatory subjects. The use of an ingestible temperature sensor in conjunction with fast and accurate cosinor analysis provides a noninvasive method to mark menstrual phases, including the critical preovulatory period.

The Circadian Rhythm of Core Temperature: Origin and some Implications for Exercise Performance

2005 ◽  
Vol 22 (2) ◽  
pp. 207-225 ◽  
Author(s):  
Jim Waterhouse ◽  
Barry Drust ◽  
Dietmar Weinert ◽  
Benjamin Edwards ◽  
Warren Gregson ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Core Temperature ◽  
Exercise Performance

11 Circadian Rhythm of Core Temperature, Blood Pressure and Heart Rate in Hypothyroid and Normal Rats

2015 ◽  
pp. 55-59
Author(s):  
P De Remigis ◽  
P Cugini ◽  
F Halberg ◽  
S Sensi ◽  
D Scavo
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Circadian Rhythm ◽  
Core Temperature

scholarly journals Circadian tau differences and rhythm associations in delayed sleep–wake phase disorder and sighted non-24-hour sleep–wake rhythm disorder

SLEEP ◽  
2020 ◽  
Author(s):  
Gorica Micic ◽  
Nicole Lovato ◽  
Sally A Ferguson ◽  
Helen J Burgess ◽  
Leon Lack
Keyword(s):  
Circadian Rhythm ◽  
Core Body Temperature ◽  
Sleep Onset ◽  
Phase Relationship ◽  
Biological Rhythms ◽  
Circadian Phase ◽  
Behavioral Rhythm ◽  
Rhythm Disorder ◽  
Dim Light ◽  
Delayed Sleep

Abstract Study Objectives We investigated biological and behavioral rhythm period lengths (i.e. taus) of delayed sleep–wake phase disorder (DSWPD) and non-24-hour sleep–wake rhythm disorder (N24SWD). Based on circadian phase timing (temperature and dim light melatonin onset), DSWPD participants were dichotomized into a circadian-delayed and a circadian non-delayed group to investigate etiological differences. Methods Participants with DSWPD (n = 26, 17 m, age: 21.85 ± 4.97 years), full-sighted N24SWD (n = 4, 3 m, age: 25.75 ± 4.99 years) and 18 controls (10 m, age: 23.72 ± 5.10 years) participated in an 80-h modified constant routine. An ultradian protocol of 1-h “days” in dim light, controlled conditions alternated 20-min sleep/dark periods with 40-min enforced wakefulness/light. Subjective sleepiness ratings were recorded prior to every sleep/dark opportunity and median reaction time (vigilance) was measured hourly. Obtained sleep (sleep propensity) was derived from 20-min sleep/dark opportunities to quantify hourly objective sleepiness. Hourly core body temperature was recorded, and salivary melatonin assayed to measure endogenous circadian rhythms. Rhythm data were curved using the two-component cosine model. Results Patients with DSWPD and N24SWD had significantly longer melatonin and temperature taus compared to controls. Circadian non-delayed DSWPD had normally timed temperature and melatonin rhythms but were typically sleeping at relatively late circadian phases compared to those with circadian-delayed DSWPD. Conclusions People with DSWPD and N24SWD exhibit significantly longer biological circadian rhythm period lengths compared to controls. Approximately half of those diagnosed with DSWPD do not have abnormally delayed circadian rhythm timings suggesting abnormal phase relationship between biological rhythms and behavioral sleep period or potentially conditioned sleep-onset insomnia.

Changes with Age Characterize Circadian Rhythm in Telemetered Core Temperature of Stroke-Prone Rats

1981 ◽  
Vol 36 (1) ◽  
pp. 28-30 ◽  
Author(s):  
J. Halberg ◽  
E. Halberg ◽  
P. Regal ◽  
F. Halberg
Keyword(s):  
Circadian Rhythm ◽  
Core Temperature

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).

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