Nav: Home

Using an air conditioner in summer may affect sleep quality

February 16, 2017

A study by a joint research team including professor Kazuyo Tsuzuki of Toyohashi University of Technology, Department of Architecture and Civil Engineering, National Institute of Advanced Industrial Science and Technology and Asahi Kasei Homes revealed that airflow from an air conditioner (AC) stimulates the human body while sleeping and impacts on sleep conditions even if the mean airflow velocity is lower than an insensible level. It suggests some AC setting may have an unintentional negative impact on sleep quality despite the comfort the person feels.

Urban warming blocks the temperature at night from cooling. It causes sweltering nights and deteriorates sleep quality. However, high-quality sleep can still be realized if the room temperature is controlled effectively with an AC. The general belief is that having the AC on all night is bad for health. Also, quite a few of us experience chills while sleeping and awakening due to cold temperature.

Airflow velocity in the sleeping environment can be configured with the AC. However, no data on airflow velocity measurement or research on the influence of AC airflow have been available.

The research team, led by professor Kazuyo Tsuzuki, had the subjects sleep in two bedrooms set to the same temperature using ACs set at different airflow velocities, then made a comparison of the depth of sleep and body temperature control using electroencephalogram (EEG) measurements as well as subjective reporting by the subjects.

We call the air velocity of 0.2m/s or lower "insensible airflow", in a sense, the person remains unaware of such a low level of airflow. In this study, a comparison was made on the influence of two types of airflow, mean velocity of 0.14 m/s (general AC) and 0.04 m/s (customized AC), both at a room temperature of 26 °C. Subjects felt cooler with the higher airflow velocity during wakefulness and sleep. However, no significant difference was observed in the feeling of comfort, length of sleep depth, skin temperature, rectal temperature or sense of warmth or coolness in each subject before sleeping. General AC lowers airflow when the room temperature reaches the desired setting and starts increasing the flow again when the temperature is higher. The study compared the correlation between the timing of the airflow starting to blow and body movement, heart rate and waking stage in sleep depth. The results found that the subjects have significantly greater body movements, an increased heart rate and a higher frequency of waking in the room that has the AC with a mean velocity of 0.14 m/s. This suggests the general AC may have some influence on sleep, as we discovered that subjects roll over or their sleep depth changes the moment cool air blows out.

This study was conducted using healthy adult male subjects. It implies that the cold airflow may have a greater impact on the overall sleep of female and elderly subjects with lower physical strength or a greater sensitivity to cold. The result of this study is expected to be a useful clue as to how to configure the airflow velocity of an AC to create a comfortable sleeping environment.

This research is the result of the study conducted by Professor Kazuyo Tsuzuki at the National Institute of Advanced Industrial Science and Technology.

The research results were reported online in the Energy and Buildings journal on December 23, 2016.
-end-
Reference:

Morito, N., Tsuzuki, K., Mori, I., and Nishimiya, H. (2017). Effects of two kinds of air conditioner airflow on human sleep and thermoregulation. Energy and Buildings, 138, 490-498., DOI: 10.1016/j.enbuild.2016.12.066

Funding: This research was conducted with the Grants-in-Aid for Scientific Research #21300271 and #25282016 by Ministry of Education, Culture, Sports, Science and Technology and Japan Society for the Promotion of Science.

Further information:

Toyohashi University of Technology
1-1 Hibarigaoka, Tempaku
Toyohashi, Aichi Prefecture, 441-8580, JAPAN
Inquiries: Committee for Public Relations
E-mail: press@office.tut.ac.jpToyohashi University of Technology, which was founded in 1976 as a National University of Japan, is a leading research institute in the fields of mechanical engineering, advanced electronics, information sciences, life sciences, and architecture.

Website: http://www.tut.ac.jp/english/

Toyohashi University of Technology

Related Sleep Articles:

Baby sleeping in same room associated with less sleep, unsafe sleep habits
The American Academy of Pediatrics (AAP) recommends parents keep babies in the same room with them to sleep for the first year to prevent sudden infant death syndrome (SIDS).
Alternating skimpy sleep with sleep marathons hurts attention, creativity in young adults
Skimping on sleep, followed by 'catch-up' days with long snoozes, is tied to worse cognition -- both in attention and creativity -- in young adults, in particular those tackling major projects, Baylor University researchers have found.
Sleep trackers can prompt sleep problems
A researcher and clinician in the sleep disorders program in the Department of Behavioral Sciences at Rush University Medical Center and an associate professor at Rush University, Baron says use of these devices follows a pattern reflected in the title of the Sleep Medicine study: 'Orthosomnia: Are Some Patients Taking the Quantified Self Too Far?'
UW sleep research high-resolution images show how the brain resets during sleep
Striking electron microscope pictures from inside the brains of mice suggest what happens in our own brain every day: Our synapses -- the junctions between nerve cells -- grow strong and large during the stimulation of daytime, then shrink by nearly 20 percent while we sleep, creating room for more growth and learning the next day.
What is good quality sleep? National Sleep Foundation provides guidance
The National Sleep Foundation (NSF) recently released the key indicators of good sleep quality, as established by a panel of experts.
Homeless sleep less, more likely to have insomnia; sleep improvements needed
The homeless sleep less and are more likely to have insomnia and daytime fatigue than people in the general population, findings researchers believe suggest more attention needs to be paid to improving sleep for this vulnerable population, according to a research letter published online by JAMA Internal Medicine.
Losing sleep over discrimination? 'Everyday discrimination' may contribute to sleep problems
People who perceive more discrimination in daily life have higher rates of sleep problems, based on both subjective and objective measures, reports a study in Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society.
Mouse mutants with sleep defects may shed light on the mysteries of sleep
The first unbiased genetic screen for sleep defects in mice has yielded two interesting mutants, Sleepy, which sleeps excessively, and Dreamless, which lacks rapid eye movement (REM) sleep.
Brain circuit that drives sleep-wake states, sleep-preparation behavior is identified
Stanford University School of Medicine scientists have identified a brain circuit that's indispensable to the sleep-wake cycle.
Recharge with sleep: Pediatric sleep recommendations promoting optimal health
For the first time, the American Academy of Sleep Medicine has released official consensus recommendations for the amount of sleep needed to promote optimal health in children and teenagers to avoid the health risks of insufficient sleep.

Related Sleep Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Moving Forward
When the life you've built slips out of your grasp, you're often told it's best to move on. But is that true? Instead of forgetting the past, TED speakers describe how we can move forward with it. Guests include writers Nora McInerny and Suleika Jaouad, and human rights advocate Lindy Lou Isonhood.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...