Evidence map›Paper›PMID 41462246›Full record

Observational studyBMC medicine2025

Effect of nighttime bedroom temperature on heart rate variability in older adults: an observational study.

Fergus K O'Connor, Aaron J E Bach, Connor Forbes, Shannon Rutherford, Sebastian Binnewies, Surendran Sabapathy, Norman R Morris

Abstract readObservational Study
PubMed Full text at PMC Publisher
In one paragraph

Observational study in BMC medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.

0numbers the graph read from it
0cells of the map it votes in
5citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

5 citing papers in PubMed.

  1. Trial
  2. Article
  3. Article
  4. Article
  5. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

7 authors.

Fergus K O'ConnorSchool of Allied Health, Sport and Social Work, Griffith University, 1 Parklands Dr, Southport, QLD, 4215, Australia. f.oconnor@griffith.edu.au.
Aaron J E BachSchool of Allied Health, Sport and Social Work, Griffith University, 1 Parklands Dr, Southport, QLD, 4215, Australia.
Connor ForbesSchool of Information and Communication Technology, Griffith University, Gold Coast, QLD, Australia.
Shannon RutherfordSchool of Medicine and Dentistry, Griffith University, Gold Coast, QLD, Australia.
Sebastian BinnewiesSchool of Information and Communication Technology, Griffith University, Gold Coast, QLD, Australia.
Surendran SabapathySchool of Allied Health, Sport and Social Work, Griffith University, 1 Parklands Dr, Southport, QLD, 4215, Australia.
Norman R MorrisSchool of Allied Health, Sport and Social Work, Griffith University, 1 Parklands Dr, Southport, QLD, 4215, Australia.

Funding

Wellcome Trust 224709Wellcome Trust 224709/Z/21/Z
6 · The paper itself

Abstract

backgroundClimate change is increasing the frequency of hot nights, which may contribute to cardiovascular morbidity and mortality by impairing sleep and autonomic recovery. Despite World Health Organization guidelines for maximum daytime indoor temperatures (26 °C, 79 °F), there are no equivalent recommendations for nighttime conditions. We investigated the impact of nocturnal bedroom temperature on heart rate and heart rate variability (HRV) in free-living older adults.

methodsIn this observational study, 47 community-dwelling adults aged ≥ 65 years in southeast Queensland, Australia, were monitored across one summer (December 2024-March 2025). Wearable devices recorded heart rate and HRV during nighttime periods of sleep between the hours of 9 PM-7 AM, while in-home sensors continuously measured bedroom temperature. The primary outcome was the natural logarithm of the root mean square of successive differences (lnRMSSD). Secondary outcomes were log-transformed frequency-domain HRV indices (high frequency: lnHF, low frequency: lnLF, low to high frequency ratio: lnLF:HF) and heart rate. Generalised mixed effects models analysed associations between wearable derived outcomes and temperature categories (< 24 °C [79 °F], 24-26 °C [75-79 °F], 26-28 °C [79-82 °F], 28-32 °C [82-90 °F]). Clinically relevant thresholds were defined as ≥ 1.5 standard deviation change in HRV or ≥ 5 beats·min⁻

resultsAcross 14,179 valid nighttime hours, median bedroom temperature was 25.9 °C (Q1, Q3; 24.6, 26.9). Compared with < 24 °C (79 °F), nighttime bedroom temperatures of 24-26 °C (75-79 °F; odds ratio: 1.4; 95% confidence interval [1.2, 1.6], P < 0.001), 26-28 °C (79-82 °F; 2.0 [1.8-2.3]) and 28-32 °C (82-90 °F; 2.9 [2.5-3.4]) were associated with greater odds of clinically relevant reductions in lnRMSSD (P < 0.001). Higher temperatures were also linked to reduced lnHF and lnLF, increased ln(LF:HF), and elevated heart rate (all P < 0.001).

conclusionsNocturnal bedroom temperatures above 24 °C (79 °F) were associated with greater likelihood of autonomic disruption and increased heart rate in older adults, consistent with a shift toward sympathetic dominance and heightened physiological stress, with greater effects observed as temperature increased. These findings provide real-world physiological evidence supporting the development of nighttime indoor temperature guidelines to protect vulnerable populations in a warming climate.

Indexed as

Heart RateTemperatureAgedAged, 80 and overFemaleHumansIndependent LivingMaleQueenslandSleepWearable Electronic DevicesAutonomic stressHeat stressIndoor temperatureThermoregulation

Identifiers

PMID41462246
PMCPMC12751657

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.