Rhythm Of Skin Temperature Research Articles

Circadian Rhythm of Distal Skin Temperature in Healthy Older and Young Women and Its Relationship with Sleep-Wake Rhythm and Environmental Factors under Natural Living Conditions.

Little is known about the healthy aging of the circadian timing system under natural living conditions. This study explores changes in the circadian rhythm of distal skin temperature (DST) with aging and relates these changes to sleep-wake timing and environmental influences. DST, sleep-wake timing, 24-h light exposure, and physical activity were measured and averaged over seven consecutive days using temperature sensors, actigraphy with a light meter, and sleep diaries in 35 healthy older women (60-79 years) and 30 young women (20-34 years). Circadian rhythm characteristics, describing strength (amplitude) and timing (acrophase) of the DST rhythm, were calculated using cosinor analysis. The older adults displayed an 18-19% smaller amplitude and a 66-73 min earlier acrophase (peak time) for DST rhythm than the young adults, indicating a weaker and phase-advanced DST rhythm. The phase advance for DST was not due to an earlier evening increase, but to a shorter nocturnal plateau period. Daytime light exposure inversely affected strength (amplitude) but not phasing of the DST rhythm in older adults. The DST rhythm was 3.5 times more advanced than the sleep-wake rhythm, showing an altered phase relationship (phase angle) between both rhythms with aging. The phase angle was more heterogeneous among older adults, showing differential aging. The phase advance for DST rhythm and the altered and heterogeneous phase relationship between DST and sleep-wake rhythms were not related to ambient light exposure and the physical activity of older adults. This suggests that healthy aging of the circadian system might be due to endogenous mechanisms such as an internal rearrangement rather than external influences.

Menstrual cycle phases and dosage of synthetic hormonal contraceptives influence diurnal rhythm characteristics of distal skin temperature

ABSTRACT This study aimed to explore how natural menstrual cycle phases and dosage of oral hormonal contraceptives (OC) influence the diurnal rhythm of distal skin temperature (DST) under real-life conditions. Participants were 41 healthy females (23.9 ± 2.48 y), comprising 27 females taking monophasic hormonal oral contraceptives (OC users) and 14 females with menstrual cycles (non-OC users). Wrist DST was continuously recorded and averaged over two consecutive 24-hour days during (pseudo)follicular and (pseudo)luteal menstrual phases. Diurnal rhythm characteristics, i.e. acrophase and amplitude, describing timing and strength of the DST rhythm, respectively, were calculated using cosinor analysis. Results show that non-OC users experienced earlier diurnal DST maximum (acrophase, p = 0.019) and larger amplitude (p = 0.016) during the luteal phase than during the follicular phase. This was observed in most (71.4%) but not all individuals. The OC users showed no differences in acrophase or amplitude between pseudoluteal and pseudofollicular phases. OC users taking a higher dosage of progestin displayed a larger amplitude for DST rhythm during the pseudoluteal phase (p = 0.009), while estrogen dosage had no effect. In conclusion, monophasic OC cause changes in diurnal DST rhythm, similar to those observed in the luteal phase of females with menstrual cycles, suggesting that synthetic progestins act in a similar manner on skin thermoregulation as progesterone does.

0295 Association between circadian rhythm of skin temperature and actigraphic sleep in free-living conditions: the HEIJO-KYO study

Abstract Introduction Skin temperature manipulation with little or no change in core body temperature affects sleep-wake states. However, the significance of 24-hour variation in skin temperature to sleep quality is unclear. We aimed to evaluate whether the circadian rhythm of distal skin temperature (DST) affects sleep quality in free-living conditions and to provide additional evidence about the relationship between thermal input to the skin and sleep-wake states. Methods In this cross-sectional study of 2,177 community-dwelling adults (Mean age 68.8 [SD 8.0] years), we measured DST using a temperature logger (Thermochron iButton, Maxim) at 3-minute intervals for seven consecutive days to calculate non-parametric indicators of circadian rhythm: intradaily variability (IV), interdaily stability (IS), and relative amplitude (RA). The participants underwent simultaneous 7-day wrist actigraphy (GT3X-BT, ActiGraph) to measure sleep objectively. The association between non-parametric indicators and 7-day means of sleep measures was evaluated using multivariable linear regression models. Results Lower quartiles of IV and higher quartiles of IS and RA were significantly associated with higher sleep efficiency, shorter wake after sleep onset, and longer total sleep time (all p <.001). After adjusting for potential confounders, including physical activity and outdoor temperature, the coefficients for the linear trend of sleep efficiency were −1.07 (95% confidence interval [CI]: −1.45, −0.69), 1.08 (95% CI: 0.75, 1.41), and 1.33 (95% CI: 0.83, 1.84) in IV, IS, and RA, respectively (all p <.001). Conclusion Circadian rhythms of DST with higher fluctuation, lower regularity across days, and blunted amplitude were associated with worse sleep quality. Our findings may be applied in thermoregulatory interventions to enhance sleep quality. Support (if any)

Association between circadian skin temperature rhythms and actigraphic sleep measures in real-life settings.

Skin temperature manipulation with little or no change in core body temperature affects sleep-wake states; however, the association of 24-hour skin temperature variation with sleep quality has not been investigated in a large-scale population. We examined the association between the circadian rhythm of distal skin temperature and sleep quality in real-life settings and aimed to provide additional evidence of the link between thermoregulation and sleep-wake states. In this cross-sectional study of 2,187 community-dwelling adults, we measured distal skin temperature at the ventral forearm at 3-minute intervals for 7 consecutive days to calculate nonparametric indicators of a circadian skin temperature rhythm, including intradaily variability, interdaily stability, and relative amplitude. Participants underwent simultaneous 7-day wrist actigraphy to objectively measure sleep quality. The association between nonparametric circadian skin temperature rhythm indicators and 7-day sleep measures was evaluated using multivariable linear regression models. Lower intradaily variability and higher interdaily stability and relative amplitude of distal skin temperature were significantly associated with higher sleep efficiency, shorter wake after sleep onset, and longer total sleep time (all P < .001). After adjusting for demographic, clinical, and environmental factors, the coefficients for the linear trend of sleep efficiency were -1.20 (95% confidence interval: -1.53, -0.87), 1.08 (95% confidence interval: 0.80-1.36), and 1.47 (95% confidence interval: 1.04-1.89) per quartile increase in intradaily variability, interdaily stability, and relative amplitude, respectively (all P < .001). Distal skin temperature with lower fluctuations and higher regularity and rhythm amplitudes was associated with better sleep quality. Our results could be applied in chronobiological interventions to improve sleep quality. Tai Y, Obayashi K, Yamagami Y, Saeki K. Association between circadian skin temperature rhythms and actigraphic sleep measures in real-life settings. J Clin Sleep Med. 2023;19(7):1281-1292.

Infrared methodologies for the assessment of skin temperature daily rhythm in two domestic mammalian species.

To assess the accuracy of infrared methodologies for daily rhythm monitoring of skin temperature, five clinically healthy Italian Saddle gelding horses, and five not pregnant and not lactating Camosciata goats, were monitored every 4h over a 48h period. The horses were housed in individual boxes, while the goats in two indoor pens, under natural photoperiod and natural environmental temperature. In each animal, skin temperature was recorded with the use of a digital infrared camera and a non-contact infrared thermometer, in five regions: neck, shoulder, ribs, flank and croup. Recorded values were compared with the well-established daily rhythm of rectal temperature. Rectal temperature was recorded at the same time by means of a digital thermometer. In horses, a lower value of skin temperature was recorded using the infrared thermometer for the croup region compared to shoulder and flank; a lower value of skin temperature was recorded using thermography for the croup region compared to the shoulder. In goats, a lower value of skin temperature was recorded using the infrared thermometer for the croup region compared to the flank. In both species, higher values of rectal temperature were observed, compared to the temperature recorded at the skin regions using the other two methodologies. Cosinor rhythmometry showed a daily rhythm of rectal and skin temperature recorded using both methodologies in all the examined regions. General linear model (GLM) showed statistically significant effect of breed on all rhythmic parameters; of day of monitoring on amplitude; of site of recording (rectal vs skin regions) on mesor, amplitude and acrophase; and no effect of methodologies used. The results of this study show the differences in rhythmicity of various body regions temperature and their differences in comparison with daily rhythm rectal temperature. The use of infrared methodologies was inaccurate in assessing body core temperature, but its use could be considered for the evaluation of inflammation in the different body sites.

The Effect of Exercise Timing on Glycemic Control: A Randomized Clinical Trial.

This study sought to determine the effect of diurnal exercise timing on glycemic control in individuals enrolled in a 12-wk supervised multimodal exercise training program. A secondary aim was to determine the effect of diurnal exercise timing on the circadian rhythm of wrist skin temperature. Forty sedentary, overweight adults (mean ± SD, age = 51 ± 13 yr; body mass index = 30.9 ± 4.2 kg·m; women, n = 23) with and without (n = 20) T2D diagnosis were randomly allocated to either a morning (amEX) or an evening (pmEX) exercise training group. The supervised 12-wk (3 d·wk) program, comprised 30 min of moderate-intensity walking and 4 resistance-based exercises (3 sets, 12-18 repetitions each). Glycemic outcomes (glycated hemoglobin, fasting glucose, postprandial glucose) and wrist skin temperature were assessed at baseline and postintervention. Exercise training improved (main effect of time, all P < 0.01) all glycemic outcomes; however, this was independent of allocation to either the amEX (Hedge's g, 0.23-0.90) or the pmEX (Hedge's g, 0.16-0.90) group. Accordingly, the adopted exercise training program did not alter the circadian rhythm of skin temperature. When only T2D individuals were compared, amEX demonstrated greater effects (all Hedge's g) on glycated hemoglobin (amEX, 0.57; pmEX, 0.32), fasting glucose (amEX, 0.91; pmEX, 0.53), and postprandial glucose (amEX, 1.12; pmEX, 0.71) but was not statistically different. Twelve weeks of multimodal exercise training improved glycemic control and postprandial glycemic responses in overweight non-T2D and T2D individuals. However, no distinct glycemic benefits or alterations in circadian rhythm were associated with morning versus evening exercise, when performed three times per week in this cohort.

Relationship between the Daily Rhythm of Distal Skin Temperature and Brown Adipose Tissue 18F-FDG Uptake in Young Sedentary Adults.

The present study examines whether the daily rhythm of distal skin temperature (DST) is associated with brown adipose tissue (BAT) metabolism as determined by 18F-fluorodeoxyglucose (18F-FDG) uptake in young adults. Using a wireless thermometer (iButton) worn on the nondominant wrist, DST was measured in 77 subjects (26% male; age 22 ± 2 years; body mass index 25.2 ± 4.8 kg/m2) for 7 consecutive days. The temperatures to which they were habitually exposed over the day were also recorded. The interday stability of DST was calculated from the collected data, along with the intraday variability and relative amplitude; the mean temperature of the 5 and 10 consecutive hours with the maximum and minimum DST values, respectively; and when these hours occurred. Following exposure to cold, BAT volume and mean and peak standardized 18F-FDG uptake (SUVmean and SUVpeak) were determined for each subject via static 18F-FDG positron emission tomography/computed tomography scanning. Relative amplitude and the time at which the 10 consecutive hours of minimum DST values occurred were positively associated with BAT volume, SUVmean, and SUVpeak (p ≤ 0.02), whereas the mean DST of that period was inversely associated with the latter BAT variables (p ≤ 0.01). The interday stability and intraday variability of the DST were also associated (directly and inversely, respectively) with BAT SUVpeak (p ≤ 0.02 for both). All of these associations disappeared, however, when the analyses were adjusted for the ambient temperature to which the subjects were habitually exposed. Thus, the relationship between the daily rhythm of DST and BAT activity estimated by 18F-FDG uptake is masked by environmental and likely behavioral factors. Of note is that those participants exposed to the lowest ambient temperature showed 3 to 5 times more BAT volume and activity compared with subjects who were exposed to a warmer ambient temperature.

Circadian skin temperature rhythms, circadian activity rhythms and sleep in individuals with self-reported depressive symptoms

BackgroundDisturbed circadian rhythms have been associated with depression. New body-worn devices allow the objective recording of circadian parameters such as physical activity, skin temperature and sleep. The objective of this study was to investigate whether circadian skin temperature and circadian activity rhythms are altered in depressed individuals. MethodsData on skin temperature, physical activity and sleep were available for 1610 subjects from a population-based cohort study. In a matching process two groups were formed for analysis: 121 participants with pronounced depression symptoms (CES-D Score > 21) and n = 121 matched non-depressed controls (CES-D Score < 15). Circadian rhythms were investigated by analyzing non-parametric rhythm indicators of 24-h skin temperature and physical activity data. Sleep timing, continuity and quantity were calculated from actigraphy. ResultsNo differences between the groups were found when all participants were considered. After excluding antidepressant medicated participants, the depression group was found to have a lower skin temperature amplitude t(208) = 2.45, p = .015 and a less stable skin temperature rhythm t(208) = 2.40, p = .017. The amplitude predicted the group status (beta = −5.529, p = .016). No effects were found for activity or sleep. ConclusionThe results indicate that skin-temperature rhythms are blunted in unmedicated depressed individuals. This could be a promising non-invasive marker for further analysis.

Circadian Rhythmic Characteristics in Men With Substance Use Disorder Under Treatment. Influence of Age of Onset of Substance Use and Duration of Abstinence.

There is evidence of the reciprocal influence between the alteration of circadian rhythms and Substance Use Disorders (SUD), and part of the success of the SUD treatment lays in the patient's rhythmic recovery. We aim to elucidate the effect of the SUD treatment in circadian rhythmicity considering, for the first time, the age of onset of substance use (OSU) and duration of abstinence. We registered the sleep-wake schedules, the chronotype and the distal skin temperature of 114 SUD patients with at least 3 months of abstinence, considering whether they had begun consumption at age 16 or earlier (OSU ≤ 16, n = 56) or at 17 or later (OSU ≥ 17, n = 58), and duration of abstinence as short (SA: 3 to 5 months, n = 38), medium (MA: 6 to 9 months, n = 35) or long (LA: more than 9 months, n = 41). Moreover, we compared the patients' distal skin temperature pattern with a similar sample of healthy controls (HC, n = 103). SUD patients showed a morningness tendency and higher night values, amplitude and stability, a better adjustment to the cosine model and lower minimum temperature and circadianity index in the distal skin temperature rhythm, in contrast to the HC group. The OSU ≥ 17 and LA groups showed a more robust distal skin temperature pattern, as well as milder clinical characteristics when compared to the OSU ≤ 16 and SA groups, respectively. The circadian disturbances associated to substance consumption seem to improve with treatment, although the age of OSU and the duration of abstinence are modulating variables. Our results highlight the need to include chronobiological strategies that boost circadian rhythmicity both in SUD prevention and rehabilitation programs. The measurement of distal skin temperature rhythm, a simple and reliable procedure, could be considered an indicator of response to treatment in SUD patients.

Multidimensional Circadian Monitoring by Wearable Biosensors in Parkinson's Disease.

Parkinson’s disease (PD) is associated with several non-motor symptoms that may precede the diagnosis and constitute a major source of frailty in this population. The digital era in health care has open up new prospects to move forward from the qualitative and subjective scoring for PD with the use of new wearable biosensors that enable frequent quantitative, reliable, repeatable, and multidimensional measurements to be made with minimal discomfort and inconvenience for patients. A cross-sectional study was conducted to test a wrist-worn device combined with machine-learning processing to detect circadian rhythms of sleep, motor, and autonomic disruption, which can be suitable for the objective and non-invasive evaluation of PD patients. Wrist skin temperature, motor acceleration, time in movement, hand position, light exposure, and sleep rhythms were continuously measured in 12 PD patients and 12 age-matched healthy controls for seven consecutive days using an ambulatory circadian monitoring device (ACM). Our study demonstrates that a multichannel ACM device collects reliable and complementary information from motor (acceleration and time in movement) and common non-motor (sleep and skin temperature rhythms) features frequently disrupted in PD. Acceleration during the daytime (as indicative of motor impairment), time in movement during sleep (representative of fragmented sleep) and their ratio (A/T) are the best indexes to objectively characterize the most common symptoms of PD, allowing for a reliable and easy scoring method to evaluate patients. Chronodisruption score, measured by the integrative algorithm known as the circadian function index is directly linked to a low A/T score. Our work attempts to implement innovative technologies based on wearable, multisensor, objective, and easy-to-use devices, to quantify PD circadian rhythms in huge populations over extended periods of time, while controlling at the same time exposure to exogenous circadian synchronizers.

Daily rhythm of skin temperature of women evaluated by infrared thermal imaging

It is well known that skin temperature varies due to circadian rhythm. Although there is information available for men, little is known about women's circadian rhythm in the analysis of skin temperature (Tsk) using infrared thermography. The objective of this study is to identify Tsk variations on different body regions in women through infrared thermography during the day. The sample consisted of 20 female (mean age of 20.5 ± 1.3 years, body weight of 62.2 ± 9.2kg and height of 165.0 ± 4.7cm). Oneway ANOVA for repeated measures, and Cosinor analysis was used to determine the MESOR, amplitude and acrophase of Tsk. The regions of the forearm, upper arm and anterior and posterior legs in the lower limbs, as well as the chest and scapulae in the upper limbs showed higher variability throughout the day. In general, distal regions had lower values compared with the central regions, and the pectoral region had the lowest standard deviation values. Tsk of the analyzed regions at different times show significant differences between periods of the day in young active women, showing the minimum absolute values for both Tsk in the early morning. These results highlight the need to consider the time of day when analyzing women's skin temperature. Future studies should report the time of day when the images were collected, as well as consider the circadian rhythm when making comparisons.

Abnormalities in the 24-hour rhythm of skin temperature in cirrhosis: Sleep-wake and general clinical implications.

Sleep preparation/onset are associated with peripheral vasodilatation and a decrease in body temperature. The hyperdynamic syndrome exhibited by patients with cirrhosis may impinge on sleep preparation, thus contributing to their difficulties falling asleep. The aim of this study was the assessment of skin temperature, in relation to sleep-wake patterns, in patients with cirrhosis. Fifty-three subjects were initially recruited, and 46 completed the study. Of the final 46, 12 were outpatients with cirrhosis, 13 inpatients with cirrhosis, 11 inpatients without cirrhosis and 10 healthy volunteers. All underwent baseline sleep-wake evaluation and blood sampling for inflammatory markers and morning melatonin levels. Distal/proximal skin temperature and their gradient (DPG) were recorded for 24hours by a wireless device. Over this period subjects kept a sleep-wake diary. Inpatients with cirrhosis slept significantly less well than the other groups. Inpatients and outpatients with cirrhosis had higher proximal temperature and blunted rhythmicity compared to the other groups. Inpatients with/without cirrhosis had higher distal temperature values and blunted rhythmicity compared to the other groups. Inpatients and outpatients with cirrhosis had significantly lower DPG values compared to the other groups, and DPG reached near-zero values several hours later. Significant correlations were observed between temperature and sleep-wake variables and inflammatory markers. Alterations of distal/proximal skin temperature, their gradient and their time-course were observed in patients with cirrhosis, which may contribute to their sleep disturbances.

Skin Temperature Rhythms in Humans Respond to Changes in the Timing of Sleep and Light.

Body temperature is known to vary with circadian phase and to be influenced by factors that can mask its circadian expression. We wanted to test whether skin temperature rhythms were sensitive to an abrupt shift of the sleep schedule and to the resetting effects of light. Nineteen healthy subjects spent 6 days in time isolation and underwent a simulated night-shift procedure. They were assigned to either a control group ( n = 10) or bright light group ( n = 9) and measurements were taken under a baseline day-oriented schedule and during the 4th cycle of a night-oriented schedule. In the bright light group, participants were exposed to a 3-cycle 8-h exposure of ~6,500 lux at night, while the control group remained in dim light conditions (~3 lux). Skin temperature was recorded in 10 and 4 participants from the control and bright light groups, respectively. We found significant circadian rhythms of plasma melatonin, core body temperature (CBT), and skin temperature at baseline for both groups ( p < 0.001 for all). Rhythms of melatonin, CBT, and skin temperature following night shifts were significantly phase delayed by about 7 to 9 h ( p < 0.05) in response to bright light at night, whereas there was no shift in the control group. In addition, we found that at bedtime melatonin does not consistently increase before the increase in distal skin temperature and subsequent decrease in CBT, in contrast to what has been previously reported. The present study shows that, in constant posture conditions, skin temperature rhythms have an evoked component sensitive to abrupt changes in the timing of sleep. They also comprise an endogenous component that is sensitive to the resetting effects of bright light exposure. These results have applications for the determination of circadian phase, as skin temperature is less intrusive than rectal temperature recordings.

Deprivation of plasma estradiol level affects circadian rhythms of body core and tail skin temperature in female rats

PurposeWe aimed to assess the effect of estradiol on daily changes of thermoregulatory responses of the tail vasculature in ovariectomized rats.MethodsFemale Wistar rats (n=10, age of 8‐12 wk) were bilaterally ovariectomized, and placed a telemetry device for the measurements of body core temperature (Tcore) and spontaneous activity (ACT) in the abdominal cavity. Temperature of the tail surface (Ttail) was estimated by thermography. Two silicon tubes containing 17β‐estradiol (E2, 50mg) were subcutaneously placed in one group (n=5, E2 (+)), and empty tubes were placed in the other group (n=5, E2 (‐)). The tubes were removed 10 days after the surgery. Tcore, ACT, and Ttail were measured a day before and 14 days after the removal of the tubes (PRE and Day 14, respectively). Regression analysis was conducted for the relationship between the daily values of Tcore and Ttail.ResultsOn the PRE, Tcore was higher (P&lt;0.05) in the E2 (‐) group than in the E2 (+) group at 12:30‐17:00 (37.2±0.2°C and 36.5±0.2°C, respectively). Ttail was higher (P&lt;0.05) in the E2 (‐) group than the E2 (+) group at 20:00‐0:30 (33.4±0.3°C and 31.2±0.6°C, respectively). The regression slope for Ttail and Tcore was greater (P&lt;0.05) in the E2 (‐) group than in the E2 (+) group on the PRE (1.41±0.34 and 0.60±0.16, respectively). On Day 14, in the E2 (‐) group, circadian rhythms of Tcore and Ttail remained unchanged from those on the PRE. Tcore and Ttail were higher than those on PRE at 14:30‐18:30 and 19:00‐18:30, respectively. The regression slope was greater (P&lt;0.05) than that of the PRE.ConclusionA reduction of estradiol affects circadian rhythms of Tcore and Ttail. Moreover, a lack of estradiol may decrease the ability in thermoregulatory response of the tail vasculature.

Ontogeny and aging of the distal skin temperature rhythm in humans.

In circadian terms, human ontogeny is characterized by the emergence of a daily pattern, from a previous ultradian pattern, for most variables during the first 6 months of life. Circadian aging in humans is characterized by a phase advance, accompanied by rhythm fragmentation and flattening. Despite an expanding body of literature focused on distal skin temperature, little information is available about the ontogeny and practically nothing about age-related changes in this rhythm. Thus, the aim was to evaluate the degree of maturation and aging of the circadian pattern of distal skin temperature to identify those parameters that are modified throughout life and could be used to differentiate subjects according to their age. For this, distal skin temperature was measured in 197 volunteers (55 % women), including babies aged 15 days (30 subjects), 1 month (28 subjects), 3 months (31 subjects), and 6 months (10 subjects); young adults aged 19 years (37 subjects); middle-aged persons aged 46 years (27 subjects); older people aged 72 (34 subjects). Circadian system maturation was associated with an increase in amplitude and a reduction in skin temperature during sleep. During adulthood, women showed a more robust pattern (lower fragmentation, and higher night-time temperature, amplitude, circadian function index, and first harmonic relative power); however, these differences were lost with aging, a period of life that was consistently associated with a phase advance of the rhythm. In summary, distal skin temperature pattern can be used as a robust variable to discern between different ages throughout the life.

The circadian rhythm of the skin temperature in children during puberty

The results of long-term research of formation of the circadian rhythm of skin temperature (CRT) in children during puberty are described. For this purpose, the skin temperature (T) of children, adolescents, and young adults of both sexes in the age range of 8–22 years was monitored for 48 h using a Thermochron iButton device. The age-related mesor dynamics, which reflects establishment of body thermoregulation during puberty, follows a wave pattern. The first T maximum is observed in children 10–11 years of age and the second one, in adolescents 14–15 years of age. Note that the overall dynamics in boys and girls are synchronous, but the mesor for girls aged 8 to 17 years is significantly higher. In adults aged 20–22 years, men display a higher mesor value as compared to women. The dynamics of CRT amplitude is stable until the age of 12–13 years with a subsequent decrease in amplitude in boys and an increase in girls at the age of 14–15 years. The subjects of both sexes display a drastic increase in the amplitude at the age of 16–17 years and a considerable decrease by the age of maturity (20–22 years). The CRT amplitude in boys is significantly larger as compared with girls, being similar in adult males and females. Monitoring of the sleep-wake cycle has shown that diurnal thermoregulation changes at certain ages (for boys, 10–11 years and for girls, 10–11 and 16–17 years); the night temperature is higher than the day values.

Short-term influence of cataract surgery on circadian biological rhythm and related health outcomes (CLOCK-IOL trial): study protocol for a randomized controlled trial.

BackgroundLight information is the most important cue of circadian rhythm which synchronizes biological rhythm with external environment. Circadian misalignment of biological rhythm and external environment is associated with increased risk of depression, insomnia, obesity, diabetes, cardiovascular disease, and cancer.Increased light transmission by cataract surgery may improve circadian misalignment and related health outcomes. Although some observational studies have shown improvement of depression and insomnia after cataract surgery, randomized controlled trials are lacking. We will conduct a parallel-group, assessor-blinded, simple randomized controlled study comparing a cataract surgery group at three months after surgery with a control group to determine whether cataract surgery improves depressive symptoms, sleep quality, body mass regulation, and glucose and lipid metabolism.Methods/DesignWe will recruit patients who are aged 60 years and over, scheduled to receive their first cataract surgery, and have grade 2 or higher nuclear opacification as defined by the lens opacities classification system III. Exclusion criteria will be patients with major depression, severe corneal opacity, severe glaucoma, vitreous haemorrhage, proliferative diabetic retinopathy, macular oedema, age-related macular degeneration, and patients needing immediate or combined cataract surgery. After baseline participants will be randomized to two groups. Outcomes will be measured at three months after surgery among the intervention group, and three months after baseline among the control group. We will assess depressive symptoms as a primary outcome, using the short version geriatric depression scale (GDS-15). Secondary outcomes will be subjective and actigraph-measured sleep quality, sleepiness, glycated haemoglobin, fasting plasma glucose and triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, body mass index, abdominal circumference, circadian rhythms of physical activity and wrist skin temperature, and urinary melatonin metabolite. Chronotype and visual function will be assessed using the ‘morningness-eveningness’ questionnaire, the Munich chronotype questionnaire, and the National Eye Institute Visual Function Questionnaire.DiscussionAlthough there are potential limitations due to the difference in duration from baseline survey to outcome measurements between two groups, any seasonal effect on the outcome measurement will be balanced as a result of continuous inclusion of participants through the year, and outcomes will be adjusted for day length at outcome measurements at analysis.Trial registrationUMIN000014559, UMIN Clinical Trials Registry, registered on 15 July 2014.

Association between the impairment of skin temperature rhythm and hypertension

An increasing amount of bibliography relates hypertension to certain sleep disorders and reduced sleep quality. Wrist temperature (WT) circadian rhythm is related to autonomic balance, thermoregulation, sleep propensity and sleep wake cycle; hence, it has been proposed as possible screening technique to assess blood pressure (BP) dipping status. Thus, the aim of this work is to determine of hypertension is associated to changes in WT rhythm. 33 healthy subjects (21–63 years old) were monitoring for WT, Activity (A) and Position (P) by means of two data loggers, an Ibuttom device (ThermoChron®, Data loggers I- button) and a Hobo actimeter (Hobo® Pendant G, Acceleration Data Logger). Ambulatory BP was determined during 24 h using a BP monitor (Spacelabs® Medical), with a sampling rate of one measure every 20 min during day and every 40 min during night. An alertness variable (TAP) was calculated averaging normalized values for WT, A and P. Sleep time was considered when P < 30 o and A < 20 o /min. Hypertensive patients showed increased heart rate when were compared with normotensive patients (79.94 ± 2.76 bpm vs. 71.00 ± 1.84 bpm, p < 0.05) and a significant decrease in WT during sleep period (34.22 ± 0.14 o C vs. 34.63 ± 0.09 o C, p < 0.05) and lower position values during daytime (47.83 ± 1.97 o vs. 52.57 ± 1.23 o , p < 0.05) respect to normotensive subjects, while no differences were founded in activity and TAP. Hypertension is closely related to a significant impairment in WT circadian rhythm, allowing differentiating between normotensive and hypertensive patients. In fact, lower nighttime WT values are connected to sleep disorders such as insomnia or sleep disordered breathing, which are related to higher nighttime blood pressure probably due to the increase in nocturnal sympathetic activation in hypertensive patients. Study supported by RETICEF (RD12/0043/0011), MINECO (BFU2010–21945-C02–01), and INNPACTO (IPT-2011–0833-900000) with FEDER cofounding to JAM, and a research fellowship to Antonio Martinez-Nicolas (University of Murcia).

A comparison between rhythms in forehead skin and rectal (core) temperature in sedentary subjects living in a thermally neutral environment

In human circadian rhythm research, rectal temperature is the traditional gold standard for estimating core temperature, but the measurement of rectal temperature is inconvenient and unacceptable to some subjects. This study examined whether the circadian rhythm of forehead skin temperature would be an alternative to that of rectal temperature in sedentary subjects living in a thermally neutral environment. Six healthy female volunteers participated as subjects for 37.5 h, from 21:30 h on day 0 to 06:30 h on day 2. They were tested twice while wearing two different types of clothing. One type of clothing covered the whole body except the head and hands (Type L); the other exposed the head and distal extremities (Type H). Subjects lived in a climatic chamber controlled at 23.8 ± 0.2 °C and 60 ± 5% RH with light intensity of 500 lux from 06:30 to 19:30 h, 100 lux from 19:30 to 22:30 h and 0 lux from 22:30 to 06:30 h. Rectal temperature and skin temperatures at seven sites were recorded continuously at 10 min intervals. The extent to which the circadian rhythms of forehead and hand skin temperature mirrored that of rectal temperature was determined by cross-correlation and cosinor analyses. Cross-correlation analysis of data from the group or individuals, and whether wearing Type L or Type H clothing, indicated that the profile of forehead skin temperature was similar to that of rectal temperature, with highly significant positive correlation coefficients (r = 0.9099–0.9744) and time lags of 0.17–0.33 h. By contrast, the profile of hand skin temperature was approximately in antiphase, with smaller correlation coefficients (though still highly significant: r = 0.6036–0.7526), and with time lags of 11.00–14.11 h. Cosinor analysis indicated that the acrophase of the circadian rhythm of forehead skin temperature for individuals was slightly, but not significantly, earlier than that of rectal temperature with both types of clothing (0.54 ± 0.68 and 0.35 ± 0.64 h with Type L and Type H clothing, respectively). The circadian rhythm of forehead skin temperature showed a significantly greater amplitude and lower mesor than rectal temperature, whether wearing Type L or Type H clothing. Individuals’ data gave 0.38 ± 0.09 and −2.92 ± 0.31 °C, respectively, with Type L clothing and 0.40 ± 0.26 and −2.86 ± 0.35 °C with Type H clothing; these differences were not significantly different between the two types of clothing. It is concluded that, in sedentary subjects living in a thermally neutral environment, forehead skin temperature gives information regarding phase and some aspects of amplitude that can act as substitutes for rectal temperature data.

Influence of gestational diabetes on circadian rhythms of children and their association with fetal adiposity

To analyse the circadian rhythm maturation of temperature, activity and sleep during the first year of life in offspring of diabetic mothers (ODM) and its relationship with obesity markers. A prospective analysis of the children of 63 pregnant women (23 controls, 21 gestational diabetes mellitus (GDM) controlled with diet and 19 GDM with insulin). Fetal abdominal circumference was evaluated ecographically during gestation. Skin temperature and rest-activity rhythms were monitored for 3 consecutive days in children at 15 days and 1, 3 and 6 months. Anthropometrical parameters of the children were evaluated during the first year of life. Children from the GDM groups tended to higher fetal abdominal circumference z-score than controls at the beginning of the last trimester (p = 0.077) and at delivery (p = 0.078). Mean skin temperature or activity was not different among the groups. The I < O sleep index pointed to increasing concordance with parental sleeping at 3 and 6 months but no significant GDM-dependent differences. However, some of the parameters that define temperature maturation and also the circadian function index from the temperature-activity variable were significantly lower at 6 months in the GDM + insulin group. Fetal abdominal circumference z-score, as a predictor of fetal adiposity, correlated negatively with parameters related to circadian rhythm maturation as the circadian/ultradian rhythm (P1 /Pult ratio). Fetal adiposity correlated with a worse circadian rhythm regulation in ODM. In addition, ODM insulin-treated showed a disturbed pattern of the circadian function index of temperature activity at 6 months of age.