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Evening sugar intake (≥6 PM) is associated with decreased sleep efficiency in professional male rugby league athletes

In a 7-day observational study of 28 professional male rugby league athletes, each 1 g increase in sugar consumed after 6 PM was associated with a 0.21% decrease in sleep efficiency, and each 1 g/kg increase was associated with a 0.22% decrease. No other significant associations between dietary intake and sleep outcomes were found.

Last updated: Aug 26, 2026•0 RCTs•📖 Read as article →

Evidence Score

Evidence Score34/100
Human RCT☆☆☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. The Relationship Between Dietary Intake and Meal Timing on Sleep Behaviors in Professional Male Rugby League Athletes.

observational

Sharples A, Fullagar HHK, Hulin B, Duffield R · International journal of sports physiology and performance (2026)

Participants: N/A
Duration: 7 days
Intervention: Observational assessment of dietary intake (including sugar) consumed after 6 PM
Outcome: Sleep efficiency (%), total sleep time (min), wake after sleep onset (min), sleep onset latency (min)
Effect Size: N/A (reported as regression coefficients: -0.21% per g, -0.22% per g/kg)
Population: Professional male rugby league athletes during preseason

Result:

PubMed: 42632633DOI: 10.1123/ijspp.2025-0635

Mechanism Graph

Evening sugar intake may cause postprandial hyperglycemia and insulin spikes
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This can lead to nocturnal hypoglycemia and counter-regulatory hormone release
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These hormonal changes may disrupt sleep architecture and reduce sleep efficiency
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Result: Lower sleep efficiency

Limitations

  • ⚠Observational design cannot establish causality
  • ⚠Dietary intake was self-reported via smartphone app, which may have measurement errors
  • ⚠Actigraphy may overestimate sleep efficiency compared to polysomnography
  • ⚠Short monitoring period (7 days) may not capture habitual patterns

Frequently Asked Questions

Does eating sugar in the evening affect sleep in athletes?▼

Yes, this study found that higher sugar intake after 6 PM was associated with lower sleep efficiency in professional rugby league athletes.

How much sugar intake was associated with poorer sleep?▼

Each 1 g increase in evening sugar was linked to a 0.21% decrease in sleep efficiency, and each 1 g/kg increase was linked to a 0.22% decrease.

What sleep measures were affected by evening sugar intake?▼

Only sleep efficiency was significantly affected; total sleep time, wake after sleep onset, and sleep onset latency were not significantly associated.

Is this study a randomized controlled trial?▼

No, it is an observational study, so it cannot prove that sugar causes poor sleep, only that they are associated.

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References

  1. 1.Sharples A, Fullagar HHK, Hulin B, Duffield R. "The Relationship Between Dietary Intake and Meal Timing on Sleep Behaviors in Professional Male Rugby League Athletes.." International journal of sports physiology and performance, 2026. PMID: 42632633 DOI: 10.1123/ijspp.2025-0635
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.