Silence in the bedroom

Experimental study on effect of background noise on deep sleep in bedroom

Type of study: non-rct experimental

Number of citations: 0

Year: 2019

Authors: Xiang Yan, Jianghua Wang, Hui Li, Yuxiao Chen

Journal: The Journal of the Acoustical Society of America

Journal ranking: Q1

Key takeaways: Deep sleep length increases at 31 dBA, with the best value being around this level, and decreases below this level due to excessive quietness.

Abstract: One of the most important external factors for sleep quality is noise. Previous studies show that deep sleep is disturbed strongly by noise, resulting in insufficient cerebral cortex deep resting, in delaying the growth and development, and in reducing immunity and brain functions. In the past, all the research studies added artificial noise into the bedroom, and how background noise affects sleep was still unknown. In this paper, the difference in the deep sleep length between the normal bedroom and the 0-dB(A) silence room which excludes the background noise during subject’s sleep was compared. Continuously two night sleeps of 35 random subjects, wearing the EEG brainwave Zeo headband, were recorded, one in the silence room and another in subject’s self-home bedroom. The result shows that comparing 29–35 dBA with the 0 dB extreme silence condition, deep sleep length increased. The best value locates about 31 dBA, which may be related to the masking of breathing sounds. Below 31 dBA, with noise reducing, the deep sleep length is reduced because of the excessive quietness reduces the masking effect, highlighting the effects of incidental noise. Between 31 and 48 dBA, as the noise increases, the length of deep sleep would decrease, by 4% for each additional 1 dB noise.

The impact of nocturnal road traffic noise, bedroom window orientation, and work-related stress on subjective sleep quality: results of a cross-sectional study among working women

Type of study: non-rct observational study

Number of citations: 10

Year: 2021

Authors: S. Bartels, M. Ögren, Jeong-Lim Kim, Sofie Fredriksson, K. Persson Waye

Journal: International Archives of Occupational and Environmental Health

Journal ranking: Q1

Key takeaways: Bedroom window orientation, not road noise exposure, is a more relevant predictor of poor sleep in working women, with a non-significant additive interaction between the two factors.

Abstract: To examine the effect of work-related stress and road noise exposure on self-rated sleep and potential additive interaction effects.Sleep and predictor variables were surveyed within two subsamples with 2191 and 1764 working women in a cross-sectional study. Sleep was assessed using a single question on general sleep quality and four questions on specific sleep problems and subsequently dichotomized (poor sleep vs. no poor sleep). Work-related stress was operationalized by job strain and effort-reward imbalance. Nocturnal exposure to road traffic noise was assessed as (a) the orientation of the bedroom window to a quiet façade vs. a low-, medium- or high-trafficked street and (b) energy-equivalent sound pressure levels for night-time modelled at the most exposed façade (Lnight). We distinguished between low (< 45 dB(A)), medium (45-50 dB(A)) and high exposure (> 50 dB(A)).Poor sleep was associated with job strain and effort-reward imbalance. The prevalence of poor sleep did not increase with increasing Lnight, but bedroom window orientation showed a non-significant trend. A quiet façade had a protective effect on sleep in each Lnight category. We found a non-significant trend for an additive interaction between bedroom window orientation and job strain.Noise levels modelled for the most exposed façade likely overestimate the actual exposure and thus may not be a precise predictor of poor sleep. Bedroom window orientation seems more relevant. Potential additive interaction effects between bedroom window orientation and job strain should be considered when interpreting epidemiological study results on noise-induced sleep disturbances.

The effect of noise exposure on sleep quality of urban residents: A comparative study in Shanghai, China

Type of study:

Number of citations: 10

Year: 2023

Authors: Xinbo Xu, L. Lan, Yuxiang Sun, Z. Lian

Journal: Building Simulation

Journal ranking: Q1

Key takeaways: Noise exposure significantly affects urban residents' sleep quality, affecting REM sleep duration, deep sleep duration, and subjective sleep quality, with females being more sensitive to noise exposure.

Abstract: Noise exposure is becoming extremely common in urban area, but its specific impact on sleep remains controversial. Considering the limitations of previous researches, a field study which can conduct both horizontal and longitudinal analysis was designed. Urban participants were tested during two weeks in their homes, and the noise level of bedroom was artificially regulated by changing the status of window and door. During the 1050 test nights in 75 households, noise exposure was reflected from both instrument monitoring at night and perception questionnaire in the morning, and sleep quality was accessed from actigraphy and questionnaire. The analysis results showed that, 92.3% of the bedroom acoustic environment did not meet the minimum requirements of Chinese standards, and 87.9% of subjects had ever experienced harmful noise during the test period. Furthermore, sleep quality was affected by noise exposure from the perspective of both physiological and psychological; the duration of rapid eye movement (REM) sleep was significantly (p < 0.05) shortened with the increase of sound intensity, the duration of deep sleep shortened and subjective sleep quality worsened significantly (p < 0.05) with the increase of acoustic sensation vote. In addition, females were more sensitive to noise exposure and their subjective sleep quality was more likely to be influenced by emotions. This study has important implications for acoustic environment design of bedrooms in cities, and suggested more attention should be paid to the anxiety caused by noise exposure.

Associations of bedroom PM2.5, CO2, temperature, humidity, and noise with sleep: An observational actigraphy study.

Type of study: non-rct observational study

Number of citations: 17

Year: 2023

Authors: M. Basner, Michael G Smith, Christopher W Jones, Adrian J. Ecker, K. Howard, Victoria Schneller, M. Cordoza, M. Kaizi-Lutu, Sierra Park-Chavar, A. Stahn, D. Dinges, H. Shou, Jonathan A. Mitchell, A. Bhatnagar, Ted Smith, Allison E Smith, Cameron K. Stopforth, R. Yeager, R. Keith

Journal: Sleep health

Journal ranking: Q1

Key takeaways: Higher levels of PM2.5, temperature, CO2, and noise in the bedroom decrease sleep efficiency, highlighting the importance of the bedroom environment for high-quality sleep.

The effects of bedroom air quality on sleep and next-day performance.

Type of study: non-rct experimental

Number of citations: 193

Year: 2016

Authors: P. Strøm-Tejsen, D. Zukowska, P. Wargocki, D. Wyon

Journal: Indoor air

Journal ranking: Q1

Key takeaways: Lowering CO2 levels in bedroom ventilation significantly improves sleep quality, perceived freshness, and next-day mental performance.

Abstract: The effects of bedroom air quality on sleep and next-day performance were examined in two field-intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO2 level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO2 levels exceeded 900 ppm (the resulting average CO2 level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and subjects reported their perceptions and their well-being each morning using online questionnaires. Two tests of next-day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking.

Window/door opening‐mediated bedroom ventilation and its impact on sleep quality of healthy, young adults

Type of study: non-rct experimental

Number of citations: 82

Year: 2018

Authors: A. Mishra, A. V. Ruitenbeek, M. Loomans, H. Kort

Journal: Indoor Air

Journal ranking: Q1

Key takeaways: Open window or door in a bedroom improves sleep quality and reduces awakenings, while closed window or door in a bedroom may cause increased CO2 levels and slightly cooler temperatures.

Abstract: This work examined window/door opening as means of bedroom ventilation and the consequent effect upon occupants' sleep, using data from 17 healthy volunteers. Bedroom CO2 level, temperature, and relative humidity were measured over 5 days, for two cases: open window or door (internal, bedroom door), and closed window and door. Participant filled questionnaires and sleep diary provided subjective measure of sleep quality. Actigraphy objectively monitored the participants during sleep. Additionally, a FlexSensor, placed under pillows of participants, detected movement during sleep. Average CO2 level for the Open conditions was 717 ppm (SD = 197 ppm) and for Closed conditions was 1150 ppm (SD = 463 ppm). Absolute humidity levels were similar for both conditions, while Open conditions were slightly cooler (mean = 19.7°C, SD = 1.8°C) than Closed (mean = 20.1°C, SD = 1.5°C). Results showed significant correlations (P < .001) between actigraphy data and questionnaire responses for: sleep latency (r = .45), sleep length (r = .87), and number of awakenings (r = .28). Of all analyzed sleep parameters, questionnaire-based depth of sleep (P = .002) and actigraphy-based sleep phase (P = .003) were significantly different between Open and Closed conditions.

The Influence of Bedroom CO2 Concentration on Sleep Quality

Type of study:

Number of citations: 2

Year: 2023

Authors: Rui Wang, Wei Li, Jianfeng Gao, Chaoyi Zhao, Jiazheng Zhang, Qingfeng Bie, Mingjie Zhang, Xinchang Chen

Journal: Buildings

Journal ranking: Q1

Key takeaways: Higher CO2 concentrations in a bedroom lead to reduced sleep quality, including quietness, satisfaction, and duration, as well as increased discomfort and awakenings.

Abstract: A person spends about a third of their life sleeping, and high sleep quality is very important for health. Environmental factors are one of the most important factors affecting sleep quality, and indoor carbon dioxide (CO2) concentration while sleeping has a significant effect on sleep quality. In an indoor bedroom with no open windows and no fresh air system, different numbers of people sleeping will lead to changes in indoor CO2 concentration. In order to study the changes in sleep quality caused by differences in CO2 concentration, experimental research was performed. Objective sleep quality data are collected with polysomnography (PSG) and a subjective questionnaire. The sleep quality of the subjects is tested under three different CO2 concentration levels; the average carbon dioxide concentration of three conditions is 680, 920, and 1350 ppm, which simulate a room with 1, 2, and 3 people sleeping, respectively. Other environment parameters are controlled as follows: test environment temperature is 26 ± 0.5 °C, relative humidity is 50 ± 5%, there is no obvious heat source in the test room, and the radiation temperature and air temperature difference is less than 1 °C. A total of 30 subjective tests were carried out with 10 subjects; the test lasted more than one month. The data subsequently underwent statistical analysis to determine the influence of CO2 concentration on sleep quality. The results show that as the CO2 concentration level increased, the sleep quietness and satisfaction of the subjects gradually decreased, the sleep duration gradually decreased, and symptoms such as throat discomfort, dyspnea, dry and itchy skin, difficulty falling asleep, difficulty waking up, congested nose and bad air smell become more obvious. The PSG test results showed that CO2 concentration has a significant impact on the proportion of the N3 period. According to the group of CO2 concentration conditions, the mean of the N3 period proportion under the conditions of one person, two persons, and three persons is 20.4%, 17.3%, and 14.4%, respectively. Finally, there was also an increase in turning over or awakening during sleep, indicating that sleep quality was reduced under higher CO2 concentrations.

Effect of bedroom environment on sleep and physiological parameters for individuals with good sleep quality: A pilot study

Type of study:

Number of citations: 2

Year: 2024

Authors: G. Buonanno, L. Canale, M.T. Solomon, M.G. Smith, L. Stabile

Journal: Building and Environment

Journal ranking: Q1

Key takeaways: Bedroom environment, including temperature, humidity, CO2, and pressure, significantly impacts sleep quality and physiological parameters in individuals with good sleep quality.

Association between bedroom environment and sleep quality of older adults: A winter field study

Type of study:

Number of citations: 1

Year: 2024

Authors: Yan Yan, Li Lan, Pixin Gong, Chao Guo, Zhijian Hou

Journal: Journal of Building Engineering

Journal ranking: Q1

Key takeaways: Increasing ventilation rate and avoiding low/high humidity in the bedroom are crucial for maintaining sleep quality for older adults during winter months.

Associations between bedroom environment and sleep quality when sleeping less or more than 6h: a cross sectional study during summer

Type of study:

Number of citations: 8

Year: 2024

Authors: Mengyuan Kang, Yan Yan, Haodong Zhang, Chao Guo, Xiaojun Fan, Chandra Sekhar, Zhiwei Lian, P. Wargocki, Li Lan

Journal: Building and Environment

Journal ranking: Q1

Key takeaways: Bedroom environment significantly impacts sleep quality, especially in short-sleep durations, suggesting the need for alternative solutions to natural ventilation during summer in Shanghai.

Exploring the nexus between bedroom design and sleep quality in a warming climate

Type of study: literature review

Number of citations: 4

Year: 2023

Authors: S. Emmitt

Journal: Urban Climate

Journal ranking: Q1

Key takeaways: Bedroom design plays a crucial role in sleep quality and resilience, with overheating and extreme heat affecting sleep quality in residential properties.

A single-blind field intervention study of whether increased bedroom ventilation improves sleep quality.

Type of study: non-rct experimental

Number of citations: 9

Year: 2023

Authors: Xiaojun Fan, Chenxi Liao, Kazuya Matsuo, Kevin Verniers, J. Laverge, Brecht Neyrinck, I. Pollet, L. Fang, L. Lan, C. Sekhar, P. Wargocki

Journal: The Science of the total environment

Journal ranking: Q1

Key takeaways: Increased bedroom ventilation improves sleep quality, with less deep sleep, more light sleep, and more awakenings in lower ventilation rate conditions.

Associations of bedroom air temperature and CO2 concentration with subjective perceptions and sleep quality during transition seasons.

Type of study: non-rct observational study

Number of citations: 41

Year: 2021

Authors: Xiaojing Zhang, Guanzhang Luo, Jingchao Xie, Jia-ping Liu

Journal: Indoor air

Journal ranking: Q1

Key takeaways: A slightly warm pre-sleep environment and high ventilation with low indoor CO2 concentration in naturally ventilated bedrooms during transition seasons improves sleep quality for residents.

Abstract: This field study aimed to investigate naturally ventilated bedroom environment and its effects on subjective perception and sleep quality. Totally, 104 healthy subjects living in urban areas of Beijing participated in the study for one night during transition seasons. Bedroom environment parameters, including temperature, relative humidity, and CO2 concentration, were recorded before and during sleep. Objective sleep quality was measured by Fitbit Alta 2, a wrist-type actigraphy sensor. Subjective assessments were collected by paper-based questionnaires on sleep quality and environmental perceptions. The results showed that neutral temperature for waking state (before sleep) was estimated to be 23.8°C while for sleep state it was 26.5°C. Furthermore, pre-sleep thermal sensation vote was found to be positively correlated with deep sleep percentage. Indoor air quality was correlated with sleep quality as indicated by statistically significant correlations between odor intensity assessment, air quality acceptability, average nightly CO2 concentration, and measures of sleep quality. For naturally ventilated bedrooms during transition seasons with a mild outdoor climate, present findings suggest that a bedroom with slightly warm pre-sleep environment than neutral, and with high ventilation as indicated by low indoor CO2 concentration, could be beneficial for sleep quality of residents.

A field intervention study of the effects of window and door opening on bedroom IAQ, sleep quality, and next-day cognitive performance

Type of study:

Number of citations: 27

Year: 2022

Authors: Xiaojun Fan, Chenxi Liao, Mariya P. Bivolarova, C. Sekhar, J. Laverge, L. Lan, A. Mainka, Mizuho Akimoto, P. Wargocki

Journal: Building and Environment

Journal ranking: Q1

Key takeaways: Open windows improve bedroom air quality and sleep duration, while open doors decrease CO2 concentration but do not affect NO2 levels.

Associations of bedroom temperature and ventilation with sleep quality

Type of study: non-rct observational study

Number of citations: 65

Year: 2020

Authors: J. Xiong, L. Lan, Z. Lian, R. de Dear

Journal: Science and Technology for the Built Environment

Journal ranking: Q2

Key takeaways: Bedroom temperature negatively impacts sleep efficiency and REM sleep, while bedroom CO2 concentration negatively affects deep sleep percentage, with air freshness also negatively impacting sleep quality.

Abstract: Sleep is essential for the body to recover from both physical and psychological fatigue accruing throughout the day, and to restore energy to maintain bodily functions. Bedroom environmental quality is one of the key causes of sleep disturbance, so a better understanding of the associations of bedroom temperature and ventilation rate (using CO2 as the surrogate) with sleep quality is necessary. This field study was conducted during summer in subtropical Sydney, Australia, with a sample of 48 householders, including both males and females. In addition to a questionnaire-based subjective sleep quality scales, sleep metrics were also monitored using wrist-wearable sensors. An indoor environmental quality monitoring station (SAMBA) was installed in each survey bedroom for continuous measurements of thermal and air quality parameters at 5-minute intervals for five consecutive days for each subject. The thermal sensation subjects used to characterize their night’s sleep showed no relationship with the actual thermal conditions prevailing in the bedroom while sleeping. Sleep efficiency (ratio of time asleep to time in bed) and rapid eye movement (REM) sleep (%) were both negatively correlated with bedroom operative temperature; as bedroom operative temperature increases by 1 K, the estimate of sleep efficiency and REM sleep percentage decrease by 1.036% and 1.647%, respectively. Deep sleep percentage was negatively related to bedroom CO2 concentration, with a 4.3% decrement for every 100 ppm increase in the overnight mean CO2 concentration. The deterioration in subjectively evaluated air freshness was associated with poorer self-reported sleep quality. The effect of bedroom CO2 concentration on light sleep percentage varied significantly under different bedroom operative temperature levels.

Effects of window opening on the bedroom environment and resulting sleep quality

Type of study:

Number of citations: 20

Year: 2021

Authors: Chenxi Liao, M. Delghust, P. Wargocki, J. Laverge

Journal: Science and Technology for the Built Environment

Journal ranking: Q2

Key takeaways: Sleeping with windows open can improve air quality and reduce CO2 concentrations, but may result in higher noise levels and discomfort if there are loud noise events outdoors.

Abstract: The effects of two window states (closed or open) on the bedroom environment and on sleep quality were investigated. Twenty-seven subjects (14 males and 13 females, 20–33 years old) without sleep disorders and chronic diseases participated. The subjects slept for two consecutive nights with windows open and two consecutive nights with windows closed in four dormitory rooms adapted for the purpose of this study, one person at a time. The order of exposure was balanced among participants. Bed temperature, room temperature, relative humidity (RH), carbon dioxide (CO2), particles (PM2.5), and noise were monitored during sleep. Sleep quality was measured using subjective ratings, a wrist-worn sleep tracker, and (for one group of 14 subjects only) polysomnography (PSG) for home use; snoring in this sub-group and awakenings were also registered. Higher PM2.5 and noise levels were found with windows open, while higher room temperature, RH, and CO2 levels were measured with windows closed. There were no differences between conditions in terms of objectively measured sleep stages but the subjects with the PSG attached snored significantly less and woke up significantly less often when sleeping with windows open. Start sleep time, end sleep time, total sleep time (TST) and time in bed (TIB) measured with the sleep tracker were confirmed by the measurements made using PSG, light sleep (N1 + N2) and sleep latency were in moderate agreement but there was no significant agreement for REM and deep sleep (N3). When sleeping with windows open, the subjects rated the air as fresher but reported higher noise levels, feeling less rested, a worse mental state and well-being, and their replies on the Groningen sleep quality scale indicated poorer sleep quality. There was no clear association between the performance test score and sleep quality. These results suggest that sleeping with windows open can provide some benefits by increasing ventilation with outdoor air, reducing CO2 concentrations, improving air quality as indicated by the subjectively rated air freshness and some of the parameters defining sleep quality, but it may also result in some discomfort if there are episodic loud noise events outdoors. Further studies are required to clarify the role of open windows in achieving good sleep quality.

Experimental study of the negative effects of raised bedroom temperature and reduced ventilation on the sleep quality of elderly subjects.

Type of study: non-rct experimental

Number of citations: 20

Year: 2022

Authors: Yan Yan, Haodong Zhang, Mengyuan Kang, L. Lan, Zhentao Wang, Yanbin Lin

Journal: Indoor air

Journal ranking: Q1

Key takeaways: Elevated bedroom temperatures and poor ventilation significantly reduce sleep quality in the elderly, while improved ventilation and lower temperatures enhance deep and REM sleep duration.

Abstract: This study investigated the effects of air temperature and ventilation on the sleep quality of elderly subjects and elucidated the mechanisms involved. Sixteen subjects aged over 65 years old were exposed to four conditions in a 2 × 2 design: air temperatures of 27°C and 30°C (with a ceiling fan in operation at 30°C) and two ventilation conditions (with and without mechanical ventilation) in experimental bedrooms. Their electroencephalogram, electrooculogram, chin electromyogram, electrocardiogram, respiration, oxygen saturation, and wrist skin temperature were measured continuously during sleep. Saliva samples were collected, and blood pressure was measured both before and after sleep. The results showed that at the temperature of 30°C, the total sleep time, sleep efficiency, and duration of REM sleep of the elderly decreased by 26.3 min, 5.5%, and 5.3 min, respectively, and time awake increased by 27.0 min, in comparison with 27°C, indicating that the sleep quality of the elderly is very vulnerable to heat exposure. Even a small heat load led to an overactive sympathetic nervous system and increased wrist skin temperature, which reduced sleep quality. Improving the ventilation increased the duration of deep sleep and REM sleep by 10.3 min and 3.7 min, respectively. Higher pollutant concentrations affected the respiration and autonomous nervous systems to reduce sleep quality. The benefits of improved thermal environment and ventilation on sleep quality were found to be additive. Good ventilation and the avoidance of raised temperatures in the bedroom are thus both important for the sleep quality of the elderly.

Association of bedroom environment with the sleep quality of elderly subjects in summer: A field measurement in Shanghai, China

Type of study:

Number of citations: 41

Year: 2021

Authors: Yan Yan, L. Lan, Haodong Zhang, Yuxiang Sun, Xiaojun Fan, D. Wyon, P. Wargocki

Journal: Building and Environment

Journal ranking: Q1

Key takeaways: Higher air temperature and CO2 concentration negatively impact the sleep quality of elderly subjects in summer, with air temperature being the key factor influencing sleep efficiency and REM sleep duration.

Ventilation causing an average CO2 concentration of 1,000 ppm has negative impacts on sleep: A field-lab study on healthy youth

Type of study:

Number of citations: 14

Year: 2023

Authors: Mengyuan Kang, Yan Yan, Chao Guo, Yige Liu, Xiaojun Fan, P. Wargocki, Li Lan

Journal: Building and Environment

Journal ranking: Q1

Key takeaways: Ventilation causing an average CO2 concentration of 1,000 ppm or above significantly reduces sleep quality and negatively impacts cognitive performance the next day.

The Influence of Lighting on The Bedroom Towards The Sleep Quality of Children Aged 0-5 Years

Type of study:

Number of citations: 0

Year: 2024

Authors: Risnawati Uding, Fianti Fianti, Ian Yulianti

Journal: Physics Communication

Journal ranking: Q2

Key takeaways: Bedroom lighting has a significant impact on the sleep quality of children aged 0-5 years, reducing total awakenings by an average of 2 fewer awakenings per night.

Abstract: Lighting in the bedroom is important in maintaining the quality of children's sleep. At the age of 0-5 years, a child has a sleep duration of around 11-18 hours, so it is necessary to pay attention to the lighting in the bedroom so that children have quality sleep time. This study aims to determine the effect of lighting in the bedroom on the sleep quality of children aged 0-5 years. Samples were taken randomly with the age range of children 0-5 years with the criteria of children accustomed to sleeping with the lights off as many as 6 samples.  The number of samples was adjusted to the availability of samples around the research site in Tinjomoyo village. Data collection techniques were observation and questionnaires. The parents of the sample filled out the observation sheets and questionnaires. The duration of data collection depends on how many times each sample wakes up during sleep at night, starting when the child falls asleep until 03.00 AM. The results showed that there was an effect of bedroom lighting on the sleep quality of children aged 0-5 years as indicated by a change in the child's total awakening, which is an average of 2 fewer awakenings during sleep from the lights on to the lights off.