Shifting physical training from morning to afternoon improves sleep health and morale in soldiers
In a study of 37 active-duty soldiers, shifting physical training from 6:30 AM to 2:00 PM for approximately 30 days did not change total sleep duration per 24 hours (t28 = -0.31, P = .38) but significantly improved sleep quality (PSQI; t33 = 2.60, P < .01), daytime sleepiness (Epworth; t33 = 2.88, P < .01), and insomnia symptoms (ISI; t33 = 2.14, P = .02). Morale also significantly improved (t34 = -2.04, P = .03), while stress and anxiety remained similar.
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Shifting physical training from morning to afternoon improves sleep health and morale in soldiers The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 34/100 (low).
The Claim
Shifting physical training from morning to afternoon improves sleep health and morale in soldiers
This conclusion is most relevant to: 37 active-duty U.S. Army soldiers.
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Shifting From Morning to Afternoon Physical Training Is Associated With Improved Sleep Health, Morale, and Operational Readiness in Soldiers. (Military medicine, 2026) — In a study of 37 active-duty soldiers, shifting physical training from 6:30 AM to 2:00 PM for approximately 30 days did not change total sleep duration per 24 hours (t28 = -0.31, P = .38) but significantly improved sleep quality (PSQI; t33 = 2.60, P < .01), daytime sleepiness (Epworth; t33 = 2.88, P < .01), and insomnia symptoms (ISI; t33 = 2.14, P = .02). Morale also significantly improved (t34 = -2.04, P = .03), while stress and anxiety remained similar.
How It Works
The proposed biological pathway:
- ▸Morning PT requires early wake-up, reducing opportunity for sleep
- ▸Shifting PT to afternoon allows soldiers to sleep later
- ▸Improved sleep opportunity leads to better sleep quality and reduced daytime sleepiness
- ▸Improved sleep health and morale enhance operational readiness
Who Might Benefit
Evidence fit by population:
- ▸37 active-duty U.S. Army soldiers
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Small sample size (n=37) and single military unit, limiting generalizability
- ▸No objective sleep measures (e.g., actigraphy or polysomnography); relied on self-report surveys
- ▸Potential confounding factors such as seasonal changes, workload, or leadership support not controlled
Frequently Asked Questions
Does shifting physical training to afternoon increase total sleep duration?▼
No, the study found no significant difference in total sleep duration per 24 hours between morning and afternoon PT schedules (P = .38).
What sleep outcomes improved after shifting to afternoon PT?▼
Sleep quality (PSQI), daytime sleepiness (Epworth), and insomnia symptoms (ISI) all significantly improved after ~30 days of afternoon PT.
Did afternoon PT affect mental health or morale?▼
Morale significantly improved, while stress and anxiety remained at low to moderate levels and did not differ between schedules.
How long was the intervention period?▼
Soldiers followed the morning PT schedule for ~30 days and then the afternoon PT schedule for ~30 days, with assessments at the end of each period.
References
- 1.Negash B, Krslovic K, Fong C, Carlsson K, Krauss MAJS, Jones MAJR, Burke TM, Alger SE. “Shifting From Morning to Afternoon Physical Training Is Associated With Improved Sleep Health, Morale, and Operational Readiness in Soldiers..” Military medicine, 2026. PMID: 42560254 DOI: 10.1093/milmed/usag054