Night-time sleep EEG changes following body heating in a warm bath

doi:10.1016/0013-4694(85)90022-7

Electroencephalography and Clinical Neurophysiology

Volume 60, Issue 2, February 1985, Pages 154-157

https://doi.org/10.1016/0013-4694(85)90022-7 Get rights and content

Abstract

Six healthy female volunteers (22–24 years), physically untrained (unfit), sat in baths of warm or cool water for 90 min, between 14.30 h and 17.30 h, on separate occasions. In the former condition (HOT), rectal temperature (T_r) rose by an average of 1.8°C, and in the latter (COOL), a thermoneutral condition, there was a nil T_r change. All-night sleep EEGs were monitored after both occasions and on baseline nights. Following COOL, there was no significant change in any sleep parameter. After HOT there were significant increases in: sleepiness at bed-time, slow wave sleep, and stage 4 sleep. REM sleep was reduced, particularly in the first REM sleep period.

Résumé

Six femmes volontaires, en bonne santé (22 à 24 ans), non entraînées physiquement, furent assises dans un bain d'eau chaude ou froide pour 90 min, entre 14 h 30 et 17 h 30, en 2 sessions distinctes. Dans la première situation (CHAUDE), la température rectale (T_r) s'élevait en moyenne de 1,8°C, alors que dans la seconde (FROIDE), une situation thermiquement neutre, il n'y avait pas de modification de la T_r. Les EEG de sommeil de la nuit complète furent suivis après les deux types de sessions ainsi que pendant des nuits témoins. Après une session FROIDE, il n'y avait pas de modification des paramètres du sommeil. Une augmentation significative était observée après une session CHAUDE: de l'endormissement à l'heure du coucher, du sommeil à ondes lentes et du stade 4 du sommeil. Le sommeil paradoxal était réduit, particulièrement dans sa première période d'apparition.

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Footbath has been a common form of activity in China, Egypt and India for several hundred years. The beneficial effect of footbaths on sleep has been already known. However, the optimal footbath conditions for improving sleep quality have received little attention.
To investigate the effect of water temperature and footbath duration on body temperature responses during and after footbath using a thermoregulatory modelling approach.
A classical multi-node human thermoregulation model was modified to account for human exposure to warm water locally while seated during a footbath. The model was then used to systematically examine the effects of water temperature and footbath duration on body temperature responses during footbaths as well as to estimate the most optimal footbath duration in different water temperatures to improve sleep.
This thermoregulatory modelling study revealed that the mean skin temperature after a footbath was higher than before, whereas the core temperature after footbath was lower. The higher the water temperature and duration of the footbath, the longer time that the core temperature was maintained with a decreasing trend while the core temperature was higher. The mean skin temperature would no longer rise if there was sweating during the footbath. The onset of sweating was roughly inversely proportional to the temperature of the water.
The discrete thresholds thermoregulation model was able to predict body temperature responses during a footbath. A relationship curve between sweating onset time and water temperature has been established to determine the optimal conditions of footbath, which may provide reference to facilitate sleep onset.
Does sauna bathing protect against dementia?
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Citation Excerpt :
An increased risk of dementia was associated with frequent sleep disturbances in a study of middle-aged men from Finland during a 20-year follow-up (Luojus et al., 2017). Findings from experiments which used warm water baths for passive body heating suggest that an increase in the body core temperature beneficially affects sleep, depending on the increase in body core temperature and the proximity to sleep (Horne and Reid, 1985; Bunnell et al., 1988; Liao, 2002). Potentially sauna bathing affects sleeping similarly.
Repeated heat exposure like sauna bathing is suggested to beneficially affect against dementia development. The epidemiological evidence is, however, scarce. Therefore, we studied the association between heat exposure during sauna bathing (i.e., the frequency of sauna bathing, frequency of heat sessions, length of stay in heat, sauna temperature) and the subsequent risk of dementia. A prospective cohort study was conducted based on 13,994 men and women aged 30–69 and free from dementia diagnosis from the Finnish Mobile Clinic Follow-up Survey. During a follow-up of 39 years, a total of 1805 dementia patients were diagnosed. The sauna bathing data was gathered from a questionnaire. Analyses based on the Cox model included the sauna bathing variables and the potential confounding factors. Sauna bathing frequency was related to a reduced risk of dementia after adjustment for the potential sociodemographic, lifestyle, and metabolic risk factors of dementia considered. The hazard ratio of dementia between individuals sauna bathing 9–12 times per month in comparison with those not sauna bathing or sauna bathing less than four times per month was 0.47 (95% CI = 0.25–0.88) during the first 20 years of follow-up and 0.81 (95% CI = 0.69–0.97) during the whole follow-up. The results are in line with the hypothesis that sauna bathing provides protection against dementia. Further studies are required to verify the suggested benefits of sauna bathing.
Before-bedtime passive body heating by warm shower or bath to improve sleep: A systematic review and meta-analysis
2019, Sleep Medicine Reviews
Water-based passive body heating (PBH_WB) as a warm shower or bath before bedtime is often recommended as a simple means of improving sleep. We searched PubMed, CINAHL, Cochran, Medline, PsycInfo, and Web of Science databases and extracted pertinent information from publications meeting predefined inclusion and exclusion criteria to explore the effects of PBH_WB on sleep onset latency (SOL), wake after sleep onset, total sleep time, sleep efficiency (SE), slow wave sleep, and subjective sleep quality. The search yielded 5322 candidate articles of which 17 satisfied inclusion criteria after removing duplicates, with 13 providing comparable quantitative data for meta-analyses. PBH_WB of 40–42.5 °C was associated with both improved self-rated sleep quality and SE, and when scheduled 1–2 h before bedtime for little as 10 min significant shortening of SOL. These findings are consistent with the mechanism of PBH_WB effects being the extent of core body temperature decline achieved by increased blood perfusion to the palms and soles that augments the distal-to-proximal skin temperature gradient to enhance body heat dissipation. Nonetheless, additional investigation is required because the findings regarding PBH_WB are limited by the relative scarcity of reported research, especially its optimal timing and duration plus exact mechanisms of effects.
Effects of pre-sleep thermal environment on human thermal state and sleep quality
2019, Building and Environment
Citation Excerpt :
Meanwhile, morning awakenings occur on the rising phase of the temperature rhythm, which is 2–3 h after the CBT minimum [29–31]. Previous experiments confirmed the effects of a hot bath on night sleep, resulting in significant increase in sleepiness at bed time and slow-wave sleep (SWS) [32]. Another study was designed to change subjects' thermal state before sleep by taking melatonin at night, exposing to strong light, and eating high-calorie food [33].
Sleep is physically, physiologically, and psychologically affected by several factors. The present study mainly focused on the effects of the pre-sleep thermal environment on sleep quality. The physical heat transfer between body and thermal environment determines the thermal state and thermal sensation of a subject, thereby physiologically affecting human sleep. Chamber experiments were designed to construct three different pre-sleep environments, namely, cool, neutral, and warm, with corresponding air temperatures of 23, 26, and 29 °C, respectively. The environmental condition during sleep was equally set in the entire experiment (24 °C/50%). Physiological measurements used included EEG, EOG, and EMG recordings from lights off (23:00) to lights on (7:00) to stage sleep for further analysis and seven-point skin temperature measurement. The subjects were required to fill up questionnaires before and after sleep. Results indicated that a warm pre-sleep environment led to high total sleep time (TST) and sleep efficiency (SE) and low sleep onset latencies (SOLs) and number of awakenings (NOA). Meanwhile, a cool pre-sleep environment results in low TST and SE and high SOL, WASO, and NOA. With regard to sleep stage, more deep sleep (N3 stage) and REM sleep were discovered in subjects exposed to warm environment before sleep. Subjects who stayed in warm environment before sleep exhibited the highest scores with respect to ease of falling asleep, sleep satisfaction, and ease of awakening. Therefore, a neutral-warm thermal sensation and near-zero distal–proximal temperature gradient are the important indicators of low SOL. Furthermore, the inherent mechanism was discussed in the present study.
Objectively measured habitual physical activity and sleep-related phenomena in 1645 people aged 1–91 years: The Nakanojo Community Study
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Citation Excerpt :
Deep sleep is related to brain or whole-body cooling, and such heat loss is thought to be associated with increases in brain and body temperatures during the preceding period of wakefulness. If brain and body temperatures are increased by either exercise or passive heating while a person is awake, then the amount of deep sleep is increased during the ensuing night (Horne and Reid, 1985; Horne and Staff, 1983). The amount of deep sleep is positively correlated with both body temperature at sleep onset (Berger et al., 1988) and the magnitude of the decrease in body temperature during sleep (Horne and Staff, 1983), so that even quite small changes in body temperature may influence sleep patterns.
Relationships between habitual physical activity and sleep-related phenomena were examined in 623 male and 1022 female Japanese participating in the Nakanojo Community Study, using data collected in 2012–2013. Ages ranged from infancy to very old. Daily step count and daily duration of exercise at an intensity >3 metabolic equivalents (METs) were determined by pedometer/accelerometer, 24 h/day for 1 week. Duplicate axillary temperatures were also taken on rising and when retiring. Total bed time was noted, and the efficiency of sleep determined as hours of actual sleep (from a validated pedometer/accelerometer algorithm) divided by bed time. Step counts and especially duration of activity >3 METs peaked in teenagers and decreased as age advanced (p < 0.001). Both axillary temperatures subsequently showed a gradual age-related decline (p < 0.001). The duration and efficiency of sleep also showed a small age-dependent decrease (p < 0.001). Multivariate-adjusted correlation coefficients indicated a better quality of sleep in individuals who took greater habitual physical activity. In individuals aged ≥40 years, these findings were modified by chronic disease conditions including hypertension, diabetes mellitus and hyperlipemia; after controlling statistically for potential confounders, both physical activity and axillary temperature were lower (p < 0.05 or 0.01), and the time spent lying was longer but the efficiency of sleep was poorer (p < 0.01) in those with chronic conditions. These results suggest that habitual physical activity bears an important relationship to sleep-related phenomena at all ages, with a modification of relationships by chronic disease in people aged ≥40 years.

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Short communicationNight-time sleep EEG changes following body heating in a warm bathModifications de l'EEG du sommeil nocturne après élévation de la température corporelle par un bain chaud

Abstract

Résumé

Biol. Psychol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Qualification of sleepiness: a new approach

Psychophysiology

Human sleep and tissue restitution: some qualifications and doubts

Clin. Sci.

Short communication
Night-time sleep EEG changes following body heating in a warm bathModifications de l'EEG du sommeil nocturne après élévation de la température corporelle par un bain chaud