PMID 41752284

Research
All papers

Impact of 8 Weeks of Moderate- Versus High-Intensity Interval Training on Sleep Quality

Bourgeois J, Domange C, Celie B

Question

Do 8 weeks of HIIT and MICT differ in their effects on sleep quality and cardiorespiratory fitness?

Summary

Adults assigned to 8 weeks of running-based HIIT or moderate continuous training improved PSQI sleep-quality scores and cardiorespiratory fitness, but HIIT was not better than MICT. Both groups improved VO2max and lactate-threshold measures, while BMI and blood pressure did not change. Sleep outcomes were subjective, the sample was small, and seven participants were lost or excluded before final analysis.

Methodology

  • Healthy adults aged 18-45 without sleep-disrupting obligations.
  • 25 participants.
  • Running.
  • Work intervals: 4 min at 90-95% HRmax.
  • Recovery: 3 min at 50-70% HRmax.
  • Intensity: Heart-rate-zone prescribed from CPET/lactate threshold.
  • About 38 min.
  • 2 sessions/week for weeks 1-2; then 2 HIIT sessions plus 1 MICT session/week for weeks 3-8.
  • 8 weeks.
  • Randomized two-arm exercise intervention comparing HIIT and MICT.
  • Sleep quality, Cardiorespiratory fitness, and Lactate thresholds were tracked.

Outcomes

PSQI sleep quality

Sleep quality improved over time regardless of training modality.

Time effect p=0.013, eta2=0.171; no modality difference p=0.809.

Improved

Daily perceived sleep quality

Daily app-reported sleep quality trended toward improvement but was not significant.

p=0.063; no modality difference p=0.544.

Unclear

VO2max

VO2max increased over time in both exercise modalities.

p=0.009, eta2=0.283; no significant group interaction.

Improved

BMI and blood pressure

No significant changes in BMI or blood pressure were observed.

No clear change

Insights

  • For sleep-quality goals, regular exercise consistency may matter more than HIIT versus MICT intensity.
  • Subjective sleep benefits should be presented as modest.
  • Wearable/app sleep check-ins can support monitoring but do not replace objective sleep measurement.

Limitations

  • Small sample.
  • Dropout/exclusion of seven participants.
  • Subjective sleep measures only.
  • Eight-week duration may miss longer-term adaptations.
  • No non-exercise control arm.

Safety

  • Seven participants were not retained in final analysis due to injuries, illnesses, personal reasons, or <80% attendance.
  • No detailed intervention-related adverse-event classification was reported.
  • A minimum 24 h recovery interval was enforced.