Bathing before sleep in the young and in the elderly

In this study we investigated the effects of bathing on the quality of sleep in 30 elderly people (ages 65-83 years) and in 30 young people (ages 17-22 years) in their homes. Room temperature did not vary significantly during the nights that data were acquired, ranging from 8 to 12 degrees C. After bathing and at the beginning of sleep, the mean (SE) rectal temperatures of the young and the elderly were 37.8 (0.08) and 37.5 (0.07) degrees C, respectively, and were higher by 0.7 (0.13) and 0.6 (0.07) degrees C, respectively, than when the subjects had not bathed. At the beginning of the sleep after bathing in the young subjects, skin temperature was 32.5 (0.24) and 1.5 (0.34) degrees C higher than when those subjects had not bathed. In the elderly, however, there were no significant differences in skin temperature with and without prior bathing because they used electric blankets during sleep. After bathing, the young people reported "warmth" in their hands and/or legs, while the elderly more often reported "good sleep" or "quickness of falling asleep". During the first 3 h of sleep, body movements were less frequent after bathing for both the young and the elderly subjects. The results suggest that a bath before sleep enhances the quality of sleep, particularly in the elderly.     

Effect of menopause on melatonin and alertness rhythms investigated in constant routine conditions

Although studies have reported the effects of the menstrual cycle on melatonin rhythmicity, none has investigated the effects of menopause on the melatonin rhythm. The circadian rhythm in melatonin and its relationship to subjective alertness was investigated in pre- and postmenopausal women under constant routine conditions (controlled posture, dim lighting, calorie intake, temperature, and prolonged wakefulness). Eleven healthy pre-menopausal (42+/-4 yr) and 10 postmenopausal women (55+/-2 yr) participated in the study. Salivary melatonin samples and subjective measures of alertness and sleepiness were assessed hourly during the 22 h constant routine protocol. Postmenopausal women had a significantly earlier melatonin acrophase (1.1+/-0.5 h clock time in decimal h; mean+/-SEM, p<0.05) compared to the pre-menopausal women (2.3+/-0.3 h). There was no significant difference between melatonin onset and amplitude between the pre-menopausal and postmenopausal women. Self-rated alertness declined in both study groups as the length of sleep deprivation increased. Melatonin onset preceded the onset of self-rated sleepiness in both groups. The time interval between melatonin onset and the onset of sleepiness and alertness offset was significantly greater in the postmenopausal women compared to the pre-menopausal women. In conclusion, under controlled experimental conditions the timing of the melatonin rhythm was advanced in postmenopausal women altering its phase relationship to subjective alertness and sleepiness.     

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.

Effect of Menopause on Melatonin and Alertness Rhythms Investigated in Constant Routine Conditions

Although studies have reported the effects of the menstrual cycle on melatonin rhythmicity, none has investigated the effects of menopause on the melatonin rhythm. The circadian rhythm in melatonin and its relationship to subjective alertness was investigated in pre‐ and postmenopausal women under constant routine conditions (controlled posture, dim lighting, calorie intake, temperature, and prolonged wakefulness). Eleven healthy pre‐menopausal (42±4 yr) and 10 postmenopausal women (55±2 yr) participated in the study. Salivary melatonin samples and subjective measures of alertness and sleepiness were assessed hourly during the 22 h constant routine protocol. Postmenopausal women had a significantly earlier melatonin acrophase (1.1±0.5 h clock time in decimal h; mean±SEM, p<0.05) compared to the pre‐menopausal women (2.3±0.3 h). There was no significant difference between melatonin onset and amplitude between the pre‐menopausal and postmenopausal women. Self‐rated alertness declined in both study groups as the length of sleep deprivation increased. Melatonin onset preceded the onset of self‐rated sleepiness in both groups. The time interval between melatonin onset and the onset of sleepiness and alertness offset was significantly greater in the postmenopausal women compared to the pre‐menopausal women. In conclusion, under controlled experimental conditions the timing of the melatonin rhythm was advanced in postmenopausal women altering its phase relationship to subjective alertness and sleepiness.     

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.     

Environmental and behavioral conditions of bathing among elderly Japanese

This study investigated the bathing conditions of elderly Japanese, and sought to find factors relating to regional differences in death rates from bathtub accidents. A questionnaire survey was carried out in 11 areas of Japan. Questionnaires including questions regarding the length of time since houses had been built, types of facilities, and subjects' indoor thermal sensations and behavior while bathing were distributed to detached houses in each area twice, once in summer and once in winter. Completed questionnaires were collected from approximately 160 elderly people over 65 years old. Information regarding thermal sensations of rooms in winter revealed that a prefabricated bath and insulating window glass eased the cold in the bathroom. Unexpectedly, more subjects in the southern region than in the northern region reported being cold or a little cold while bathing in winter. In the present study, thermal sensations and behaviors while bathing seemed to be more affected by facilities and the location of houses than by the sex and age of the subjects.     

Responses of capuchin monkeys (Cebus apella) to different conditions of mirror-image stimulation

Group-living brown capuchins were given mirror-image stimulation as follows: (1) mirror 1 m away; (2) mirror attached to the cage-mesh; (3) angled mirrors creating a deflected image; (4) small mirror in the cage; and (5) small, transportable mirrors. The subjects were initially interested in the mirrors in each condition, but they generally habituated to them over the course of repeated presentations. Control (non-reflective) objects were attended to less than mirrors. Facial expressions occurred mostly in Condition 2, lateral and vertical head movements in Condition 3, reaching behind the mirror in Condition 2, looking obliquely into the mirror in Conditions 4 and 5. Despite these diverse conditions of exposure to mirrors, lasting for a total of over three months, no behaviours suggesting self-recognition were seen in the monkeys.     

Upper airway neuromuscular compensation during sleep is defective in obstructive sleep apnea

Obstructive sleep apnea is the result of repeated episodes of upper airway obstruction during sleep. Recent evidence indicates that alterations in upper airway anatomy and disturbances in neuromuscular control both play a role in the pathogenesis of obstructive sleep apnea. We hypothesized that subjects without sleep apnea are more capable of mounting vigorous neuromuscular responses to upper airway obstruction than subjects with sleep apnea. To address this hypothesis we lowered nasal pressure to induce upper airway obstruction to the verge of periodic obstructive hypopneas (cycling threshold). Ten patients with obstructive sleep apnea and nine weight-, age-, and sex-matched controls were studied during sleep. Responses in genioglossal electromyography (EMG(GG)) activity (tonic, peak phasic, and phasic EMG(GG)), maximal inspiratory airflow (V(I)max), and pharyngeal transmural pressure (P(TM)) were assessed during similar degrees of sustained conditions of upper airway obstruction and compared with those obtained at a similar nasal pressure under transient conditions. Control compared with sleep apnea subjects demonstrated greater EMG(GG), V(I)max, and P(TM) responses at comparable levels of mechanical and ventilatory stimuli at the cycling threshold, during sustained compared with transient periods of upper airway obstruction. Furthermore, the increases in EMG(GG) activity in control compared with sleep apnea subjects were observed in the tonic but not the phasic component of the EMG response. We conclude that sustained periods of upper airway obstruction induce greater increases in tonic EMG(GG), V(I)max, and P(TM) in control subjects. Our findings suggest that neuromuscular responses protect individuals without sleep apnea from developing upper airway obstruction during sleep.     

Effects of room temperature on physiological and subjective responses during whole-body bathing,half-body bathing and showering

The effects of bathroom thermal conditions on physiological and subjective responses were evaluated before, during, and after whole-body bath (W-bath), half-body bath (H-bath) and showering. The air temperature of the dressing room and bathroom was controlled at 10 degrees C, 17.5 degrees C, and 25 degrees C. Eight healthy males bathed for 10 min under nine conditions on separate days. The water temperature of the bathtub and shower was controlled at 40 degrees C and 41 degrees C, respectively. Rectal temperature (Tre), mean skin temperature (Tsk), blood pressure (BP), heart rate (HR), body weight loss and blood characteristics (hematocrit: Hct, hemoglobin: Hb) were evaluated. Also, thermal sensation (TS), thermal comfort (TC) and thermal acceptability (TA) were recorded. BP decreased rapidly during W-bath and H-bath compared to showering. HR during W-bath was significantly higher than for H-bath and showering (p < 0.01). The double products due to W-bath during bathing were also greater than for H-bath and showering (p < 0.05). There were no distinct differences in Hct and Hb among the nine conditions. However, significant differences in body weight loss were observed among the bathing methods: W-bath > H-bath > showering (p < 0.001). W-bath showed the largest increase in Tre and Tsk, followed by H-bath, and showering. Significant differences in Tre after bathing among the room temperatures were found only at H-bath. The changes in Tre after bathing for H-bath at 25 degrees C were similar to those for W-bath at 17.5 degrees C and 10 degrees C. TS and TC after bathing significantly differed for the three bathing methods at 17.5 degrees C and 10 degrees C (TS: p < 0.01 TC: p < 0.001). Especially, for showering, the largest number of subjects felt "cold" and "uncomfortable". Even though all of the subjects could accept the 10 degrees C condition after W-bath, such conditions were intolerable to half of them after showering. These results suggested that the physiological strains during H-bath and showering were smaller than during W-bath. However, colder room temperatures made it more difficult to retain body warmth after H-bath and created thermal discomfort after showering. It is particularly important for H-bath and showering to maintain an acceptable temperature in the dressing room and bathroom, in order to bathe comfortably and ensure warmth.     

Effects of a Two‐Hour Change in Bedtime on the Sleep of Healthy Seniors

Some of the sleep disruption seen in seniors (>65 yrs) may be due to alteration of the circadian pacemaker phase and/or its phase angle with bedtime. The purpose of this study was to determine the effects of 2 h changes in the timing of bedtime (both earlier and later) on the sleep of seniors. Ten healthy seniors (9 F, 1 M, age 70–82 yrs) were each studied individually during three 120 h sessions (each separated by >2 weeks) in a time‐isolation laboratory. On nights 1 and 2, bedtime and rise‐time occurred at the subjects' habitual times; on nights 3–5, bedtime was specified by the experiment, but rise‐time was at the subjects' discretion (without knowledge of clock time). Under the control condition, subjects went to bed at their habitual bedtime (HBT), under the earlier bedtime condition at (HBT?2 h), and under the later bedtime condition at (HBT+2 h). Sleep was polysomnnographically recorded and rectal temperature continuously monitored. Although total sleep time increased in the earlier compared to the later condition (p<0.01), sleep efficiency decreased and wake after sleep onset increased (p<0.01). Subjective ratings of sleep were also worse under the earlier (HBT?2 h) than under later (HBT+ 2 h) condition (p<0.05). Performance did not differ between the earlier and later conditions. The larger the phase angle between actual bedtime and circadian temperature minimum (Tmin), the longer the time spent in bed and total sleep time, and the worse the sleep efficiency and subjective sleep ratings. There were no effects related to the phase angle between Tmin and rise‐time. The relative benefits of longer vs. more efficient sleep in the elderly require further investigation.     

Circadian Adaptation to Night Shift Work Influences Sleep,Performance, Mood and the Autonomic Modulation of the Heart

Our aim was to investigate how circadian adaptation to night shift work affects psychomotor performance, sleep, subjective alertness and mood, melatonin levels, and heart rate variability (HRV). Fifteen healthy police officers on patrol working rotating shifts participated to a bright light intervention study with 2 participants studied under two conditions. The participants entered the laboratory for 48 h before and after a series of 7 consecutive night shifts in the field. The nighttime and daytime sleep periods were scheduled during the first and second laboratory visit, respectively. The subjects were considered “adapted” to night shifts if their peak salivary melatonin occurred during their daytime sleep period during the second visit. The sleep duration and quality were comparable between laboratory visits in the adapted group, whereas they were reduced during visit 2 in the non-adapted group. Reaction speed was higher at the end of the waking period during the second laboratory visit in the adapted compared to the non-adapted group. Sleep onset latency (SOL) and subjective mood levels were significantly reduced and the LF∶HF ratio during daytime sleep was significantly increased in the non-adapted group compared to the adapted group. Circadian adaptation to night shift work led to better performance, alertness and mood levels, longer daytime sleep, and lower sympathetic dominance during daytime sleep. These results suggest that the degree of circadian adaptation to night shift work is associated to different health indices. Longitudinal studies are required to investigate long-term clinical implications of circadian misalignment to atypical work schedules.     

Repeated exposures to daytime bright light increase nocturnal melatonin rise and maintain circadian phase in young subjects under fixed sleep schedule

Effects of two different light intensities during daytime were examined on human circadian rhythms in plasma melatonin, core body temperature, and wrist activity under a fixed sleep schedule. Sleep qualities as indicated by polysomnography and subjective sleepiness were also measured. In the first week, under dim light conditions ( approximately 10 lx), the onset and peak of nocturnal melatonin rise were significantly delayed, whereas the end of melatonin rise was not changed. The peak level of melatonin rise was not affected. As a result, the width of nocturnal melatonin rise was significantly shortened. In the second week, under bright light conditions ( approximately 5,000 lx), the phases of nocturnal melatonin rise were not changed further, but the peak level was significantly increased. Core body temperature at the initial sleep phase was progressively elevated during the course of dim light exposure and reached the maximum level at the first night of bright light conditions. Subjective sleepiness gradually declined in the course of dim light exposure and reached the minimum level at the first day of bright light. These findings indicate that repeated exposures to daytime bright light are effective in controlling the circadian phase and increasing the peak level of nocturnal melatonin rise in plasma and suggest a close correlation between phase-delay shifts of the onset of nocturnal melatonin rise or body temperature rhythm and daytime sleepiness.     

Temporal relationships between warmth imagery and associated changes in digital pulse amplitude, skin temperature and skin temperature sensation

Temporal relationships between warmth imagery and associated psychophysiological changes were studied by recording digital pulse amplitude, skin temperature, and thermal sensations in 5 subjects. After each trial the subjects were asked whether they thought they had been successful in producing the expected mental image. During the subjectively successful imagery tasks the digital pulse amplitude and the skin temperature of the hand rose significantly. The subjective onset of imagery took place after the digital pulse amplitude had started to change but before the skin temperature had begun to rise. This implies that mental imagery of skin warming as a conscious experience is not a prerequisite of somatic change. The thermal sensation (i.e. feeling of warmth) took place while the skin temperature was rising or immediately after that. This suggests that it is not caused by the mental image per se but by activation of skin temperature receptors.     

Stability of melatonin and temperature as circadian phase markers and their relation to sleep times in humans

Circadian rhythms of core body temperature and melatonin are commonly used as phase markers of the circadian clock. Melatonin is a more stable marker of circadian phase when measured under constant routine conditions. However, little is known about the variability of these phase markers under less controlled conditions. Moreover, there is little consensus about the preferred method of analysis. The objective of this study was to assess various methods of calculating melatonin and temperature phase in subjects with regular sleep schedules living in their natural environment. Baseline data were analyzed from 42 healthy young subjects who were studied on at least two occasions. Each hospital admission was separated by at least 3 weeks. Subjects were instructed to maintain a regular sleep schedule, which was monitored for 1 week before admission by sleep logs and actigraphy. Subjects spent one habituation night under controlled conditions prior to collecting baseline temperature and melatonin measurements. The phase of the melatonin rhythm was assessed by 9 different methods. The temperature nadir (Tmin) was estimated using both Cleveland and Cosine curve fitting procedures, with and without demasking. Variability between admissions was assessed by correlation analysis and by the mean absolute difference in timing of the phase estimates. The relationship to sleep times was assessed by correlation of sleep onset or sleep offset with the various phase markers. Melatonin phase markers were more stable and more highly correlated with the timing of sleep than estimates of Tmin. Of the methods for estimating Tmin, simple cosine analysis was the least variable. In addition, sleep offset was more strongly correlated with the various phase markers than sleep onset. The relative measures of melatonin offset had the highest correlation coefficients, the lowest study-to-study variability, and were more strongly associated with sleep timing than melatonin onsets. Concordance of the methods of analysis suggests a tendency for the declining phase of the melatonin profile to be more stable and reliable than either markers of melatonin onset or measures of the termination of melatonin synthesis.     

Circadian phase estimation of chronic insomniacs relates to their sleep characteristics

The significance of the phase of circadian rhythmicity for the diagnosis of sleep disturbance was investigated in a group of 80 chronic insomniacs (59 females; mean age 34.8, range 18-59 years). In order to stay close to common clinical practice, data were collected by means of two-week sleep diaries in combination with repeated measurements of subjective alertness and oral temperature. Special measures were taken to minimize the impact of masking upon the temperature measurements. In addition, wrist activity was monitored for an overlapping period of 11 days. Measurements of oral temperature and subjective alertness were fitted with 3 (rd) -degree polynomials, for which the peak times (times of maximum) were identified. Principal Components Analysis of these peak times and the times of bed-in and wake-up for all subjects revealed that the phase estimates for the alertness and the sleep-wake rhythms had a strong interrelationship, which was independent from the temperature phase. Using the 25- and the 75-percentiles of the frequency distribution of the temperature peak times as boundaries, the subjects were classified into early (N = 18), middle (N = 37) and late (N = 19) temperature phase subgroups, which had mean peak times of 14:08 h, 17:43 h and 20:09 h, respectively. Comparisons between the early phase and the late phase subgroups showed that a significant overall MANOVA effect was mainly due to differences in total sleep time (early < late) as calculated from the log, and to differences in the mean nocturnal actigraphic count (early> late). Moreover, the subjective estimates of sleep latency (early < late) and wake after sleep onset (early > late) tended to differ between the two subgroups. The main result of this study, i.e., that insomniacs with a relatively advanced temperature phase had a relatively shorter and more restless sleep, while insomniacs with a relatively delayed temperature phase tended to experience a relatively long sleep latency, supports the conclusion that the addition of oral temperature measurements to a sleep/wake log extends its diagnostic and therapeutic applicability.     

GSM phone signal does not produce subjective symptoms

The influence of pulsed radiofrequency (RF) electromagnetic fields of digital GSM mobile phones (902 MHz, 217 Hz pulse modulation) on subjective symptoms or sensations in healthy subjects were studied in two single-blind experiments. The duration of the RF exposure was about 60 min in Experiment 1 and 30 min in Experiment 2. Each subject rated symptoms or sensations in the beginning of the experimental session and at the end of both the exposure and the nonexposure conditions. The symptoms rated were headache, dizziness, fatigue, itching or tingling of the skin, redness on the skin, and sensations of warmth on the skin. The results did not reveal any differences between exposure and non-exposure conditions, suggesting that a 30-60 min exposure to this RF field does not produce subjective symptoms in humans.     

Case study of skin temperature and thermal perception in a hot outdoor environment

Focusing on the understanding and the estimation of the biometeorological conditions during summer in outdoor places, a field study was conducted in July 2010 in Athens, Greece over 6 days at three different sites: Syntagma Square, Ermou Street and Flisvos coast. Thermo-physiological measurements of five subjects were carried out from morning to evening for each site, simultaneously with meteorological measurements and subjective assessments of thermal sensation reported by questionnaires. The thermo-physiological variables measured were skin temperature, heat flux and metabolic heat production, while meteorological measurements included air temperature, relative humidity, wind speed, globe temperature, ground surface temperature and global radiation. The possible relation of skin temperature with the meteorological parameters was examined. Theoretical values of mean skin temperature and mean radiant temperature were estimated applying the MENEX model and were compared with the measured values. Two biometeorological indices, thermal sensation (TS) and heat load (HL)—were calculated in order to compare the predicted thermal sensation with the actual thermal vote. The theoretically estimated values of skin temperature were underestimated in relation to the measured values, while the theoretical model of mean radiant temperature was more sensitive to variations of solar radiation compared to the experimental values. TS index underestimated the thermal sensation of the five subjects when their thermal vote was ‘hot’ or ‘very hot’ and overestimated thermal sensation in the case of ‘neutral’. The HL index predicted with greater accuracy thermal sensation tending to overestimate the thermal sensation of the subjects.     

Effect of a Hot Milk Drink on Movements During Sleep

The effects on sleep of a hot drink of milk and Horlicks were compared with those of hot water taken before retiring by medical student volunteers. Horlicks reduced the number of small movements made during sleep.     

A large-scale study on subjective perception of discomfort during 7 and 1.5 T MRI examinations

A study on subjective perception has been carried out in order to gain further insight into subjective discomfort and sensations experienced during 7 T magnetic resonance imaging (MRI). This study provides information about subjective acceptance, which is essential if 7 T MRI is to become a clinical diagnostic tool. Of 573 subjects who underwent 7 T MRI, 166 were also examined at 1.5 T, providing a means of discriminating field‐dependent discomfort. All subjects judged sources of discomfort and physiological sensations on an 11‐point scale (0 = no side effects, 10 = intolerable side effects) and scores were analyzed separately for exam phases, with and without table movement at each field strength. Results revealed that 7 T MRI was, in general, judged more uncomfortable than 1.5 T; however, most subjects rated the effects as being non‐critical (mean scores between 0.5 and 3.5). Significant differences were detected regarding vertigo and sweating between subjects positioned “head‐first” and “feet‐first” at 7 T (worse in “head‐first”) and between 7 and 1.5 T (worse at 7 T), with the effects being more pronounced in the moving compared to the stationary table position. The most unpleasant factor at 7 T was the extensive examination duration, while potentially field‐dependent sensations were rated less bothersome. In summary, our study indicates that although certain sensations increase at 7 T compared to 1.5 T, they are unlikely to hinder the use of 7 T MRI as a clinical diagnostic tool. Bioelectromagnetics. Bioelectromagnetics 32:610–619, 2011. © 2011 Wiley Periodicals, Inc.     

Physiological functions of the effects of the different bathing method on recovery from local muscle fatigue

Background

Recently, mist saunas have been used in the home as a new bathing style in Japan. However, there are still few reports on the effects of bathing methods on recovery from muscle fatigue. Furthermore, the effect of mist sauna bathing on human physiological function has not yet been revealed. Therefore, we measured the physiological effects of bathing methods including the mist sauna on recovery from muscle fatigue.

Methods

The bathing methods studied included four conditions: full immersion bath, shower, mist sauna, and no bathing as a control. Ten men participated in this study. The participants completed four consecutive sessions: a 30-min rest period, a 10-min all out elbow flexion task period, a 10-min bathing period, and a 10-min recovery period. We evaluated the mean power frequency (MNF) of the electromyogram (EMG), rectal temperature (Tre), skin temperature (Tsk), skin blood flow (SBF), concentration of oxygenated hemoglobin (O2Hb), and subjective evaluation.

Results

We found that the MNF under the full immersion bath condition was significantly higher than those under the other conditions. Furthermore, Tre, SBF, and O2Hb under the full immersion bath condition were significantly higher than under the other conditions.

Conclusions

Following the results for the full immersion bath condition, the SBF and O2Hb of the mist sauna condition were significantly higher than those for the shower and no bathing conditions. These results suggest that full immersion bath and mist sauna are effective in facilitating recovery from muscle fatigue.