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Completed

NCT Number: NCT06498544

HighCycle Study: Effect of High Altitude on Sleep Disordered Breathing in Women Related to Their Menstrual Cycle Phase

Prospective cohort study investigating the menstrual cycle phase (MCP) dependent sleep disordered breathing (SDB) in women travelling to 3600 m.

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Key information

Conditions

Sleep-Disordered Breathing Apnea Dyssomnias Hypoxia Nervous System Diseases Pathological Conditions, Signs and Symptoms Respiration Disorders Respiratory Tract Diseases Signs and Symptoms Signs and Symptoms, Respiratory Sleep Apnea Syndromes Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

18 year–44 year

Sex eligibility

Female

Study type

Observational

Primary location

National Center for Cardiology and Internal Medicine

Bishkek, 720040, Kyrgyzstan

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Criteria: Inclusion Criteria:

  • Healthy, non-smoking women, age 18-44 years, without any diseases and need of regular medication (including oral contraceptives).
  • BMI >18 kg/m2 and <30 kg/m2
  • Born, raised and currently living at altitudes <1000 m
  • Written informed consent
  • Premenopausal, eumenorrheic cycle

Exclusion criteria

  • Other types of contraceptives (hormonal intrauterine device, vaginal ring, subcutaneous injections or implants, among others)
  • Pregnancy or nursing
  • Anaemic (haemoglobin concentration <10g/dl)
  • Any altitude trip <4 weks before the study
  • Allergy to acetazolamide and other sulfonamides

Treatment and study plan

Exposure to 3600 m

Other

Participants will travel to and stay for 2 nights at an altitude of 3600 m.

Primary outcomes

  1. Nocturnal oxygen saturation (SpO2)

    Time frame: Night 1 at 760 m and Night 1 at 3600 m

    MCP-related difference in altitude-induced change in the mean nocturnal oxygen saturation measured by pulse oximetry.

Secondary outcomes

  1. Nocturnal oxygen desaturation index (ODI)

    Time frame: Night 1 at 760 m and Night 1 at 3600 m

    MCP-related difference in altitude-induced change in the ODI (number of ∆SpO2 >3% per hour time in bed measured by pulse oximetry).

  2. Nocturnal oxygen desaturation index (ODI)

    Time frame: Night 1 at 760 m and Night 2 at 3600 m

    MCP-related difference in altitude-induced change in the ODI (number of ∆SpO2 >3% per hour time in bed measured by pulse oximetry).

  3. Apnea/hypopnea index (AHI)

    Time frame: Night 1 at 760 m and Night 1 at 3600 m

    MCP-related difference in altitude-induced change in the mean number of apneas/hypopneas per hour.

  4. Apnea/hypopnea index (AHI)

    Time frame: Night 1 at 760 m and Night 2 at 3600 m

    MCP-related difference in altitude-induced change in the mean number of apneas/hypopneas per hour.

  5. Subjective sleep quality

    Time frame: Night 1 at 760 m and Night 1 at 3600 m

    MCP-related difference in altitude-induced change in subjective sleep quality assessed by a 100-mm visual analog scale.

  6. Subjective sleep quality

    Time frame: Night 1 at 760 m and Night 2 at 3600 m

    MCP-related difference in altitude-induced change in subjective sleep quality assessed by a 100-mm visual analog scale.

  7. Nocturnal oxygen saturation (SpO2)

    Time frame: Night 1 at 760 m and Night 2 at 3600 m

    MCP-related difference in altitude-induced change in the mean nocturnal oxygen saturation measured by pulse oximetry.

Sponsors and collaborators

Lead sponsor

University of Zurich

Other

Collaborators

  • Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
  • National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov
  • University Hospital Heidelberg

Registry information

Official study title

HighCycle Study: Effect of High Altitude on Sleep Disordered Breathing in Women Related to Their Menstrual Cycle Phase. A Prospective Cohort Study at 3600 m.

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Jul 12, 2024
Registry last updated
Jun 5, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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