Chronobiological characterization of women with primary vasospastic syndrome: body heat loss capacity in relation to sleep initiation and phase of entrainment

Women with primary vasospastic syndrome (VS), but otherwise healthy, exhibit a functional disorder of vascular regulation (main symptom: cold extremities) and often suffer from difficulties initiating sleep (DIS). Diverse studies have shown a close association between distal vasodilatation before lights off and a rapid onset of sleep. Therefore, we hypothesized that DIS in women with VS could be due to a reduced heat loss capacity in the evening, i.e., subjects are physiologically not ready for sleep. The aim of the study was to elucidate whether women having both VS and DIS (WVD) or not (controls) show different circadian characteristics (e.g., phase delay of the circadian thermoregulatory system with respect to the sleep-wake cycle). Healthy young women (n = 9 WVD and n = 9 control) completed a 40-h constant routine protocol (adjusted to habitual bedtime) before and after an 8-h sleep episode. Skin temperatures [off-line calculated as distal-proximal skin temperature gradient (DPG)] and core body temperature (CBT; rectal) were continuously recorded. Half-hourly saliva samples were collected for melatonin assay and subjective sleepiness was assessed on the Karolinska Sleepiness Scale (KSS). Compared with control, WVD showed no differences in habitual bed times, but a 1-h circadian phase delay of dim light-melatonin onset (hours after lights on: WVD 14.6 +/- 0.3 h; control 13.5 +/- 0.2 h; P = 0.01). Similar phase shifts were observed in CBT, DPG, and KSS ratings. In conclusion, WVD exhibit a phase delay of the endogenous circadian system with respect to their habitual sleep-wake cycle, which could be a cause of DIS.     

Phase relationship between skin temperature and sleep-wake rhythms in women with vascular dysregulation and controls under real-life conditions

The aim of the study was to investigate whether women with primary vascular dysregulation (VD; main symptoms of thermal discomfort with cold extremities) and difficulties initiating sleep (DIS) exhibit a disturbed phase of entrainment (Ψ) under everyday life conditions. The authors predicted a phase delay of the distal-proximal skin temperature gradient and salivary melatonin rhythms with respect to the sleep-wake cycle in women with VD and DIS (WVD) compared to controls (CON), similar to that found in their previous constant-routine laboratory data. A total of 41 young healthy women, 20 with WVD and 21 matched CON without VD and normal sleep onset latency (SOL), were investigated under ambulatory conditions (following their habitual bedtimes) during 7 days of continuous recording of skin temperatures, sleep-wake cycles monitored by actimetry and sleep-wake diaries, and single evening saliva collections for determining the circadian marker of dim light melatonin onset (DLMO). Compared to CON, WVD showed increased distal vasoconstriction at midday and in the evening, as indicated by lower distal (DIST; hands and feet) and foot-calf skin temperatures, and distal-proximal skin temperature gradients (p相似文献   

Paradoxical Results of Psychophysiological Stress Profile in Functional Somatic Syndrome: Correlation Between Subjective Tension Score and Objective Stress Response

Mind–body interactions are important in functional somatic syndromes (FSS). Therefore, in the assessment of the psychophysiological stress response in patients with FSS, both subjective feelings and psychophysiological activity should be simultaneously measured. In this study, Objective Tension Score (OTS) was defined as an objective parameter of tension; it consisted of surface electromyography and skin conductance level as indicators of muscle and mental tension, respectively. Subjective Tension Score (STS) was defined as a subjective parameter of tension. Changes in OTS and STS in response to the stress task were investigated in 30 FSS patients and 28 controls. Objective tension was significantly hyporeactive to the stress task and STS was significantly higher in the patient group than in the control group. There was a significant negative correlation between OTS response and STS in the patient group, but no significant correlation in the control group. Our results suggested the existence of dissociation between subjective and objective responses in FSS patients. This may indicate that FSS patients had difficulty with the awareness of bodily feelings, thus supporting the concept of alexisomia or escaped bodily feelings in FSS patients.     

Cutaneous warming promotes sleep onset

Sleep occurs in close relation to changes in body temperature. Both the monophasic sleep period in humans and the polyphasic sleep periods in rodents tend to be initiated when core body temperature is declining. This decline is mainly due to an increase in skin blood flow and consequently skin warming and heat loss. We have proposed that these intrinsically occurring changes in core and skin temperatures could modulate neuronal activity in sleep-regulating brain areas (Van Someren EJW, Chronobiol Int 17: 313-54, 2000). We here provide results compatible with this hypothesis. We obtained 144 sleep-onset latencies while directly manipulating core and skin temperatures within the comfortable range in eight healthy subjects under controlled conditions. The induction of a proximal skin temperature difference of only 0.78 +/- 0.03 degrees C (mean +/- SE) around a mean of 35.13 +/- 0.11 degrees C changed sleep-onset latency by 26%, i.e., by 3.09 minutes [95% confidence interval (CI), 1.91 to 4.28] around a mean of 11.85 min (CI, 9.74 to 14.41), with faster sleep onsets when the proximal skin was warmed. The reduction in sleep-onset latency occurred despite a small but significant decrease in subjective comfort during proximal skin warming. The induction of changes in core temperature (delta = 0.20 +/- 0.02 degrees C) and distal skin temperature (delta = 0.74 +/- 0.05 degrees C) were ineffective. Previous studies have demonstrated correlations between skin temperature and sleep-onset latency. Also, sleep disruption by ambient temperatures that activate thermoregulatory defense mechanisms has been shown. The present study is the first to experimentally demonstrate a causal contribution to sleep-onset latency of skin temperature manipulations within the normal nocturnal fluctuation range. Circadian and sleep-appetitive behavior-induced variations in skin temperature might act as an input signal to sleep-regulating systems.     

PHASE RELATIONSHIP BETWEEN SKIN TEMPERATURE AND SLEEP-WAKE RHYTHMS IN WOMEN WITH VASCULAR DYSREGULATION AND CONTROLS UNDER REAL-LIFE CONDITIONS

The aim of the study was to investigate whether women with primary vascular dysregulation (VD; main symptoms of thermal discomfort with cold extremities) and difficulties initiating sleep (DIS) exhibit a disturbed phase of entrainment (Ψ) under everyday life conditions. The authors predicted a phase delay of the distal-proximal skin temperature gradient and salivary melatonin rhythms with respect to the sleep-wake cycle in women with VD and DIS (WVD) compared to controls (CON), similar to that found in their previous constant-routine laboratory data. A total of 41 young healthy women, 20 with WVD and 21 matched CON without VD and normal sleep onset latency (SOL), were investigated under ambulatory conditions (following their habitual bedtimes) during 7 days of continuous recording of skin temperatures, sleep-wake cycles monitored by actimetry and sleep-wake diaries, and single evening saliva collections for determining the circadian marker of dim light melatonin onset (DLMO). Compared to CON, WVD showed increased distal vasoconstriction at midday and in the evening, as indicated by lower distal (DIST; hands and feet) and foot-calf skin temperatures, and distal-proximal skin temperature gradients (p?<?.05). WVD manifested distal vasoconstriction before lights-off that also lasted longer after lights-off than in CON. In parallel, WVD exhibited a longer SOL (p?<?.05). To define internal phase-relationships, cross-correlation analyses were performed using diurnal rhythms of wrist activity and foot skin temperature. WVD showed a phase delay in foot skin temperature (CON versus WVD: 3.57?±?17.28?min versus 38.50?±?16.65?min; p?<?.05) but not in wrist activity. This finding was validated by additional within-subject cross-correlation analyses using the diurnal wrist activity pattern as reference. DLMO and habitual sleep times did not differ between CON and WVD. The authors conclude that WVD exhibit a phase delay of distal vasodilatation with respect to their habitual sleep-wake cycle and other circadian phase markers, such as DLMO. A full factorial design will have to show whether the finding is specific to primary vascular dysregualtion, to DIS, or to their interaction. (Author correspondence: Kurt.kraeuchi@upkbs.ch)     

Estimating outdoor thermal comfort using a cylindrical radiation thermometer and an energy budget model

A mathematical model to estimate outdoor thermal comfort for humans from micrometeorological data has been formulated using the energy balance concept and the simultaneous satisfaction of four criteria for comfort from the literature: (a) a comfortable perspiration rate, (b) a comfortable core body temperature, (c) a comfortable skin temperature, and (d) a near-zero energy budget. A cylindrical modification of the globe thermometer is proposed as a simple monitor of outdoor radiation absorption for a person, and the effect of windspeed on the thermal resistance of clothing is considered. Results show a correlation coefficient of 0.91 between model output and subjective comfort ratings of 59 different situations with a variety of temperatures, insolations and windspeeds.     

Deficient Discrimination of EMG Levels and Overestimation of Perceived Tension in Chronic Pain Patients

Twenty chronic low back pain patients (CBP), twenty tension headache (THA) patients, and twenty healthy controls (HC) participated in a tension production task where subjects had to attain four levels (4, 8, 12, 16 V) of muscle tension at the m. frontalis and the m. erector spinae. Ratings of perceived tension, pain, and aversiveness as well as EMG, heart rate, and skin conductance levels were recorded. Signal detection and correlational methods revealed that the patients were deficient in muscle tension discrimination at high tension levels in both muscles. They generally overestimated low and underestimated high levels of muscle tension, especially in the CBP group. At low muscle tension levels, both healthy controls and patients showed deficient discrimination ability. Perceived muscle tension, aversiveness, and pain ratings during the tasks were higher in the patient groups. These data confirm and clarify previous reports of deficient tension perception and show concurrent overestimation of bodily symptoms in chronic musculoskeletal pain patients.     

Seasonal changes in thermal responses of urban residents to cold exposure

To determine whether urban circumpolar residents show seasonal acclimatisation to cold, thermoregulatory responses and thermal perception during cold exposure were examined in young men during January-March (n=7) and August-September (n=8). Subjects were exposed for 24 h to 22 and to 10 degrees C. Rectal (T(rect)) and skin temperatures were measured throughout the exposure. Oxygen consumption (VO(2)), finger skin blood flow (Q(f)), shivering and cold (CDT) and warm detection thresholds (WDT) were assessed four times during the exposure. Ratings of thermal sensations, comfort and tolerance were recorded using subjective judgement scales at 1-h intervals. During winter, subjects had a significantly higher mean skin temperature at both 22 and 10 degrees C compared with summer. However, skin temperatures decreased more at 10 degrees C in winter and remained higher only in the trunk. Finger skin temperature was higher at 22 degrees C, but lower at 10 degrees C in the winter suggesting an enhanced cold-induced vasoconstriction. Similarly, Q(f) decreased more in winter. The cold detection threshold of the hand was shifted to a lower level in the cold, and more substantially in the winter, which was related to lower skin temperatures in winter. Thermal sensations showed only slight seasonal variation. The observed seasonal differences in thermal responses suggest increased preservation of heat especially in the peripheral areas in winter. Blunted vasomotor and skin temperature responses, which are typical for habituation to cold, were not observed in winter. Instead, the responses in winter resemble aggravated reactions of non-cold acclimatised subjects.     

Bed climate of Korean using ondol heating system

1. 1. To examine the influence of different bed conditions (ondol sleep, bed sleep on ondol with same bedding) of the Korean ondol traditional heating system on human response during sleep, bed climates and physiological responses such as skin and rectal temperatures, weight loss, body movement and subjective sensation were measured with 4 grown-up females as subjects while they were sleeping for 7 h.

2. 2. Bed climate: Temperatures under the mattress and inside the quilt were higher on ondol while temperatures on the mattress and humidity inside the quilt were higher on the bed.

3. 3. Rectal temperature was significantly higher on ondol; skin temperature showed no major differences in relation to bed conditions. The frequency of body movements had the highest correlation with bed climate of the parameters measured.

4. 4. Mattress weight decreased on ondol and increased on the bed.

5. 5. The frequency of body movements was significantly higher in ondol sleep.

6. 6. The subjects sensation showed difference on cushion sensation between the two types of bed condition.

7. 7. To obtain the same level of comfort on both ondol and bed sleeping conditions less thermal insulating value is needed for ondol sleep.

Skin and core temperature response to partial- and whole-body heating and cooling

1. Human subjects were exposed to partial- and whole-body heating and cooling in a controlled environmental chamber to quantify physiological and subjective responses to thermal asymmetries and transients.

2. Skin temperatures, core temperature, thermal sensation, and comfort responses were collected for 19 local body parts and for the whole body.

3. Core temperature increased in response to skin cooling and decreased in response to skin heating.

4. Hand and finger temperatures fluctuated significantly when the body was near a neutral thermal state.

5. When using a computer mouse in a cool environment, the skin temperature of the hand using the mouse was observed to be 2–3 °C lower than the unencumbered hand.     

Functional link between distal vasodilation and sleep-onset latency?

Thermoregulatory processes have long been implicated in initiation of human sleep. The purpose of this study was to evaluate the role of heat loss in sleep initiation, under the controlled conditions of a constant-routine protocol modified to permit nocturnal sleep. Heat loss was indirectly measured by means of the distal-to-proximal skin temperature gradient (DPG). A stepwise regression analysis revealed that the DPG was the best predictor variable for sleep-onset latency (compared with core body temperature or its rate of change, heart rate, melatonin onset, and subjective sleepiness ratings). This study provides evidence that selective vasodilation of distal skin regions (and hence heat loss) promotes the rapid onset of sleep.     

Thermal sensation at index finger while applying external pressure at upper arm

In this study we focused on thermal sensation at fingertip under the influence of applied external pressure via a tourniquet at the upper arm. The perceived thermal sensation has found to be closely related to the skin temperature (Tsk) that is regulated by the skin blood flow (SkBF), whereas SkBF is easily influenced by external pressure. We thus hypothesized that the perceived thermal sensation, the Tsk and SkBF form such a cross-coupled triad that jointly affects our feeling of thermal comfort. Such interconnections among them were examined in this study using two protocols to investigate the perceived thermal sensation from a given heat stimulus under an exerted external pressure: (1) the SkBF and Tsk, at the right hand index finger under different external pressures at the right upper arm of one male subject, were monitored by a laser-Doppler flowmeter (LDF); (2) subjective thermal feelings (cold, normal and warm) at the right index fingertip of 10 test takers were recorded, while contacting a glass tube filled with water at different temperatures, with/without 50 mm Hg external pressure at the upper arm, while the temperatures of the glass tube and the index fingertip were recorded by an infrared camera. First, it is found that the SkBF and Tsk at the index fingertip reduced significantly with high external pressure applied at the upper arm, while the pressure from our daily clothing is not large enough to generate such an effect. Next, the applied pressure suppresses the variations in subjective sensory responses towards the thermal stimuli. Our hypothesis on the interconnections among the perceived thermal sensation, the Tsk and SkBF is thus confirmed. Overall, females appear more discerning to temperature change under the given conditions compared to males.     

Effects of thermal underwear on thermal and subjective responses in winter

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.     

A relationship between heat loss and sleepiness: effects of postural change and melatonin administration

Kräuchi, Kurt, Christian Cajochen, and AnnaWirz-Justice. A relationship between heat loss and sleepiness:effects of postural change and melatonin administration.J. Appl. Physiol. 83(1): 134-139, 1997.Both the pineal hormone melatonin (Mel) and postural changeshave thermoregulatory sequelae. The purpose of the study was toevaluate their relationship to subjective sleepiness. Eight healthyyoung men were investigated under the unmasking conditions of aconstant routine protocol. Heart rate, rectal temperature(T_re), skin temperatures (foot,T_fo; and stomach), and subjectivesleepiness ratings were continuously recorded from 1000 to 1700. Mel (5 mg po) was administered at 1300, a time when Mel should not phaseshift the circadian system. Both the postural change at1000 from upright to a supine position (lying down in bed) and Meladministration at 1300 reduced T_reand increased T_fo in parallel withincreased sleepiness. These findings suggest that under comfortableambient temperature conditions, heat loss via the distal skin regions(e.g., feet) is a key mechanism for induction of sleepiness as corebody temperature declines.

     

Thermal comfort conditions in the morning and in the evening

Eight females and eight males participated each in 4 comfort experiments on 4 different days. Two experiments took place in the morning and two in the evening. In each experiment (21/2 hours) the preferred ambient temperature was determined for each subject by adjusting the ambient temperature according to his wishes. The subjects were sedentary. Skin temperatures, rectal temperature and evaporative weight loss were measured. Although the rectal temperature and the mean skin temperature were slightly higher in the evening than in the morning the subjects did not prefer an ambient temperature which was different from that in the morning. This indicates that the same thermal comfort conditions can be used from morning to evening.     

The Response of Human Thermal Sensation and Its Prediction to Temperature Step-Change (Cool-Neutral-Cool)

This paper reports on studies of the effect of temperature step-change (between a cool and a neutral environment) on human thermal sensation and skin temperature. Experiments with three temperature conditions were carried out in a climate chamber during the period in winter. Twelve subjects participated in the experiments simulating moving inside and outside of rooms or cabins with air conditioning. Skin temperatures and thermal sensation were recorded. Results showed overshoot and asymmetry of TSV due to the step-change. Skin temperature changed immediately when subjects entered a new environment. When moving into a neutral environment from cool, dynamic thermal sensation was in the thermal comfort zone and overshoot was not obvious. Air-conditioning in a transitional area should be considered to limit temperature difference to not more than 5°C to decrease the unacceptability of temperature step-change. The linear relationship between thermal sensation and skin temperature or gradient of skin temperature does not apply in a step-change environment. There is a significant linear correlation between TSV and Q_loss in the transient environment. Heat loss from the human skin surface can be used to predict dynamic thermal sensation instead of the heat transfer of the whole human body.     

Effects of alcohol and coca on foot temperature responses of highland Peruvians during a localized cold exposure

Two groups of highland Quechua Indian males were tested under conditions of local foot exposure to cold air (0°C). Foot temperatures were monitored throughout the hour cold test and for 16 minutes recovery at room temperature (24°C). In the first group (age range 14–20 years), 29 subjects were tested while chewing coca leaves and while under control conditions. The second group (age range 20–50 years) of 25 subjects was tested while consuming 1.1 gm of ethyl alcohol per kilogram of body weight and again under control conditions. Both drugs (coca and alcohol) are habitually consumed by members of the native population. The mastication of coca leaves had no effect on foot skin temperatures. Alcohol consumption, however, elevated foot temperatures to between 4 and 6°C higher than control values at the end of 60 minutes of cold exposure. It is suggested that alcohol consumption gives the Indian a slight thermal advantage and increases levels of comfort during natural cold exposure.     

Predominance of distal skin temperature changes at sleep onset across menstrual and circadian phases

Menstrual cycle-associated changes in reproductive hormones affect body temperature in women. We aimed to characterize the interaction between the menstrual, circadian, and scheduled sleep-wake cycles on body temperature regulation. Eight females entered the laboratory during the midfollicular (MF) and midluteal (ML) phases of their menstrual cycle for an ultradian sleep-wake cycle procedure, consisting of 36 cycles of 60-minute wake episodes alternating with 60-minute nap opportunities, in constant bed-rest conditions. Core body temperature (CBT) and distal skin temperature (DT) were recorded and used to calculate a distal-core gradient (DCG). Melatonin, sleep, and subjective sleepiness were also recorded. The circadian variation of DT and DCG was not affected by menstrual phase. DT and DCG showed rapid, large nap episode-dependent increases, whereas CBT showed slower, smaller nap episode-dependent decreases. DCG values were significantly reduced for most of the wake episode in an overall 60-minute wake/60-minute nap cycle during ML compared to MF, but these differences were eliminated at the wake-to-nap lights-out transition. Nap episode-dependent decreases in CBT were further modulated as a function of both circadian and menstrual factors, with nap episode-dependent deceases occurring more prominently during the late afternoon/evening in ML, whereas nap episode-dependent DT and DCG increases were not significantly affected by menstrual phase but only circadian phase. Circadian rhythms of melatonin secretion, DT, and DCG were significantly phase-advanced relative to CBT and sleep propensity rhythms. This study explored how the thermoregulatory system is influenced by an interaction between circadian phase and vigilance state and how this is further modulated by the menstrual cycle. Current results agree with the thermophysiological cascade model of sleep and indicate that despite increased CBT during ML, heat loss mechanisms are maintained at a similar level during nap episodes, which may allow for comparable circadian sleep propensity rhythms between menstrual phases.     

Effects of bathing and hot footbath on sleep in winter

The effects of daily bathing and hot footbath (immersion of feet in hot water) in winter on the sleep behavior of nine healthy female volunteers were studied. Subjects were assigned to three sleep conditions: sleep after bathing (Condition B), sleep after hot footbath (Condition F), and sleep without either treatment (Control). Polysomnograms (consisting of electroencephalograph, electrooculograph, and electromyograph) were obtained, and body movements during sleep were measured while monitoring both the rectal and skin temperatures of subjects. In addition, subjective sleep sensations were obtained with a questionnaire answered immediately by the subjects on awakening. The rectal temperature increased by approximately 1.0 degree C under Condition B, but this elevation was not observed under Condition F compared with Control. In contrast, the respective increases in the mean skin temperature of participants subjected to bathing and hot footbath were greater than those of Control, although these temperature differences became negligible 2 h after subjects went to bed. The sleep onset latency was shortened under both conditions compared with Control. Body movements during the first 30 min of sleep in Control were greater than under the other conditions. Rapid eye movement (REM) sleep decreased under Condition B compared with Condition F, and stage 3 was greater under the latter condition compared with Control. As such, the subjective sleep sensations were better under the two treatment conditions. These results suggest that both daily bathing and hot footbath before sleeping facilitates earlier sleep onset. A hot footbath is especially recommendable for the handicapped, elderly, and disabled, who are unable to enjoy regular baths easily and safely.     

Circadian preference modulates the neural substrate of conflict processing across the day

Human morning and evening chronotypes differ in their preferred timing for sleep and wakefulness, as well as in optimal daytime periods to cope with cognitive challenges. Recent evidence suggests that these preferences are not a simple by-product of socio-professional timing constraints, but can be driven by inter-individual differences in the expression of circadian and homeostatic sleep-wake promoting signals. Chronotypes thus constitute a unique tool to access the interplay between those processes under normally entrained day-night conditions, and to investigate how they impinge onto higher cognitive control processes. Using functional magnetic resonance imaging (fMRI), we assessed the influence of chronotype and time-of-day on conflict processing-related cerebral activity throughout a normal waking day. Sixteen morning and 15 evening types were recorded at two individually adapted time points (1.5 versus 10.5 hours spent awake) while performing the Stroop paradigm. Results show that interference-related hemodynamic responses are maintained or even increased in evening types from the subjective morning to the subjective evening in a set of brain areas playing a pivotal role in successful inhibitory functioning, whereas they decreased in morning types under the same conditions. Furthermore, during the evening hours, activity in a posterior hypothalamic region putatively involved in sleep-wake regulation correlated in a chronotype-specific manner with slow wave activity at the beginning of the night, an index of accumulated homeostatic sleep pressure. These results shed light into the cerebral mechanisms underlying inter-individual differences of higher-order cognitive state maintenance under normally entrained day-night conditions.