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Sleep continuity is crucial for fatigue and sustained attention during cold-environment military training

First-year cadets with higher physical activity and less total sleep showed increased fatigue and declines in sustained attention (PVT reaction time) and jump performance, while second-year cadets with more sleep showed partial recovery. Perceived fatigue increased post-first training block only in first-year cadets (p=0.003), and increased fatigue correlated negatively with PVT performance (all p<0.043).

Last updated: Jul 14, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score32/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. The relationship between sleep, fatigue and performance during sub-Arctic operations: data from a winter military field exercise in Finland.

observational

Varesco G, Ojanen T, Vaara JP, Martin A, van Cutsem J, Haman F, Pattyn N, Simonelli G · BMJ military health (2026)

Participants: N/A
Duration: Winter military exercise with two training blocks
Intervention: Comparison of first-year (combat role) and second-year (officer duties) cadets during a winter military exercise with differing training loads and sleep environments (heated tents vs. barracks)
Outcome: Total sleep per night, perceived fatigue (10 cm VAS), sustained attention (20-minute PVT reaction time), physical performance (standing long jump), physical activity, and environmental conditions (temperature, PM10, CO2)
Effect Size: N/A
Population: First-year and second-year cadets during a winter military field exercise in Finland

Result:

PubMed: 42431682DOI: 10.1136/military-2026-003283

Mechanism Graph

High training workload and challenging sleep environment (temperature fluctuations ~30°C, elevated PM10) disrupt sleep continuity
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Reduced total sleep and sleep continuity increase perceived fatigue
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Increased fatigue impairs sustained attention (PVT) and physical performance (jump)
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Result: Poor sleep environment combined with high training loads impairs fatigue resistance and performance

Limitations

  • ⚠Observational design; causality cannot be established
  • ⚠Small sample size and specific military context limit generalizability to civilian populations

Frequently Asked Questions

What was the main finding about sleep and performance?▼

First-year cadets with less total sleep and higher physical activity showed increased fatigue and declines in sustained attention and jump performance, while second-year cadets with more sleep showed partial recovery.

How was fatigue measured in this study?▼

Fatigue was measured using a 10 cm Visual Analogue Scale (VAS).

What type of attention task was used?▼

A 20-minute psychomotor vigilance task (PVT) was used to measure sustained attention.

Did the sleep environment affect the results?▼

Yes, accommodation in tents showed large temperature fluctuations (~30°C) and elevated particulate matter (PM10), while barracks had increased CO2, contributing to a challenging sleep environment.

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References

  1. 1.Varesco G, Ojanen T, Vaara JP, Martin A, van Cutsem J, Haman F, Pattyn N, Simonelli G. "The relationship between sleep, fatigue and performance during sub-Arctic operations: data from a winter military field exercise in Finland.." BMJ military health, 2026. PMID: 42431682 DOI: 10.1136/military-2026-003283
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.