E2 ModerateModerate confidencePEM not requiredCross-SectionalPeer-reviewedReviewed
Standard · 3 min
Core body temperature is normal in chronic fatigue syndrome.
Hamilos, D L, Nutter, D, Gershtenson, J et al. · Biological psychiatry · 1998 · DOI
Quick Summary
Many people with ME/CFS report feeling like they have a low body temperature or mild fever, but this study found that their actual core body temperature is normal. Researchers continuously measured body temperature every 5 minutes for 24 hours in people with ME/CFS and compared them to healthy people, those with allergies, and those with depression. All groups had similar normal temperatures and similar daily temperature patterns.
Why It Matters
This study addresses a common symptom reported by ME/CFS patients and provides objective data that core body temperature dysfunction is not a primary physiological abnormality in the condition. Understanding which symptoms have measurable physiological correlates and which do not helps guide future research toward actual disease mechanisms and informs clinical interpretation of patient-reported symptoms.
Observed Findings
24-hour mean core body temperature was similar across all groups: CFS 37.04±0.31°C, controls 37.00±0.17°C, allergy 37.15±0.18°C, depression 37.16±0.18°C (not significantly different)
Peak and trough circadian temperatures showed no statistically significant differences between groups
All groups demonstrated similar normal circadian rhythm patterns in core body temperature
Serum cortisol showed similar circadian profiles across all groups with peak at 08:00
All subjects had normal basal metabolic rates, thyroid function, and 24-hour urinary free cortisol excretions
Inferred Conclusions
Core body temperature is normal in ME/CFS despite frequent patient self-reports of subnormal temperature and low-grade fever
Temperature-related symptoms in ME/CFS do not reflect abnormalities in core body temperature regulation or circadian temperature rhythm
Circadian rhythm abnormalities in cortisol secretion do not explain core temperature abnormalities in ME/CFS
Remaining Questions
Why do ME/CFS patients report subnormal temperature and fever if core temperature is normal—could peripheral temperature, temperature perception, or other mechanisms be involved?
Would repeated 24-hour measurements over weeks or months reveal longer-term temperature abnormalities or dysregulation patterns?
What This Study Does Not Prove
This study does not prove that temperature-related symptoms are psychological or imaginary; subjective temperature sensations may reflect peripheral circulation changes, altered temperature perception, or other mechanisms not captured by core temperature measurement. A single 24-hour measurement period may not detect longer-term temperature abnormalities or temperature dysregulation during specific activities. The study also does not address whether temperature abnormalities exist in ME/CFS subpopulations or during post-exertional malaise.
Tags
Symptom:FatigueTemperature Dysregulation
Biomarker:Blood Biomarker
Method Flag:Small SampleStrong PhenotypingWeak Case Definition
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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