Evidence map›Paper›PMID 42118805›Full record

Observational studyPloS one2026

Impact of temperature, humidity, dehydration, and psychological stress on salivary flow and xerostomia in young men: An observational study.

Kayoko Ito, Kaname Nohno, Saori Funayama, Kouji Katsura, Noboru Kaneko, Keiko Tanaka, Makoto Inoue

Abstract readObservational Study
In one paragraph

Observational study in PloS one, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing 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

2 citing papers in PubMed.

  1. Review
  2. 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.

Kayoko ItoOral Rehabilitation, Niigata University Medical and Dental Hospital, Niigata, Japan.ORCID https://orcid.org/0000-0002-7511-3945
Kaname NohnoDivision of Oral Science for Health Promotion, Niigata University Graduate School of Medicine, Dentistry and Health Sciences, Niigata, Japan.
Saori FunayamaOral Rehabilitation, Niigata University Medical and Dental Hospital, Niigata, Japan.
Kouji KatsuraDepartment of Oral Radiology, Niigata University Medical and Dental Hospital, Niigata, Japan.
Noboru KanekoDivision of Preventive Dentistry, Niigata University Graduate School of Medicine, Dentistry and Health Sciences, Niigata, Japan.
Keiko TanakaDepartment of Patient Synthesis Support Center, Niigata University Medical & Dental Hospital, Niigata, Japan.
Makoto InoueOral Rehabilitation, Niigata University Medical and Dental Hospital, Niigata, Japan.ORCID https://orcid.org/0000-0002-6503-2973

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Xerostomia, or subjective oral dryness, is commonly reported and may occur with or without objectively reduced salivary secretion (hyposalivation). To assess salivary gland function, the salivary flow rate must be repeatedly measured over time under consistent conditions. However, given that temperature and humidity vary throughout the year, standardized measurement is difficult. Some reports have indicated that the unstimulated salivary flow rate is lower in summer than in winter, although no studies have evaluated this pattern in conjunction with humidity or dehydration. This longitudinal observational study aimed to determine the extent to which room temperature, relative humidity, body dehydration, and psychological stress are associated with unstimulated and stimulated salivary flow rates and xerostomia in healthy young men (n = 39). A questionnaire was administered to collect data regarding participants' body mass index, medical history, medications, and degree of xerostomia (severe, moderate, mild, or none). Unstimulated and stimulated salivary flow rates, salivary cortisol and chromogranin A concentrations, urine specific gravity, room temperature, and relative humidity were measured. Psychological stress was assessed via measurements of salivary cortisol and chromogranin A concentrations. Urine specific gravity served as an indicator of hydration status. Factors influencing the salivary flow rate and xerostomia were analyzed using generalized estimating equations. The unstimulated salivary flow rate was significantly associated with temperature (p = 0.008), humidity (p = 0.039), urine specific gravity (p = 0.045), and chromogranin A concentration (p < 0.001); the stimulated salivary flow rate was not significantly linked to these factors. Furthermore, xerostomia was only related to chromogranin A concentration (p = 0.012). These results suggest that indoor environmental conditions and hydration status should be considered when interpreting changes in unstimulated salivary flow rate over time; subjective oral dryness (xerostomia) showed a significant association only with chromogranin A in this exploratory study.

Indexed as

DehydrationHumiditySalivaStress, PsychologicalTemperatureXerostomiaAdultChromogranin AHumansHydrocortisoneLongitudinal StudiesMaleSalivationYoung AdultChromogranin AHydrocortisone

Identifiers

PMID42118805
PMCPMC13166909

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Registered trials

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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.