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

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.

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

Study Overview

• Status: Completed
• Conditions: Sleep-Disordered Breathing
• Intervention / Treatment: Other: Exposure to 3600 m

• Study Type: Observational
• Enrollment (Actual): 91

Contacts and Locations

Study Locations

• Kyrgyzstan
  • Bishkek
    • Bishkek, Bishkek, Kyrgyzstan, 720040
      • National Center for Cardiology and Internal Medicine

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Healthy, non-smoking, premenopausal women, age 18-44 years, without any disease and need of regular medication (including oral contraceptives).

Description

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

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Women in luteal MCP; Women being in their luteal MCP on the day of ascent to high altitude.	Other: Exposure to 3600 m; Participants will travel to and stay for 2 nights at an altitude of 3600 m.
Women in follicular MCP; Women being in their follicular MCP on the day of ascent to high altitude.	Other: Exposure to 3600 m; Participants will travel to and stay for 2 nights at an altitude of 3600 m.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Nocturnal oxygen saturation (SpO2)	MCP-related difference in altitude-induced change in the mean nocturnal oxygen saturation measured by pulse oximetry.	Night 1 at 760 m and Night 1 at 3600 m

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Nocturnal oxygen desaturation index (ODI)	MCP-related difference in altitude-induced change in the ODI (number of ∆SpO2 >3% per hour time in bed measured by pulse oximetry).	Night 1 at 760 m and Night 1 at 3600 m
Nocturnal oxygen desaturation index (ODI)	MCP-related difference in altitude-induced change in the ODI (number of ∆SpO2 >3% per hour time in bed measured by pulse oximetry).	Night 1 at 760 m and Night 2 at 3600 m
Apnea/hypopnea index (AHI)	MCP-related difference in altitude-induced change in the mean number of apneas/hypopneas per hour.	Night 1 at 760 m and Night 1 at 3600 m
Apnea/hypopnea index (AHI)	MCP-related difference in altitude-induced change in the mean number of apneas/hypopneas per hour.	Night 1 at 760 m and Night 2 at 3600 m
Subjective sleep quality	MCP-related difference in altitude-induced change in subjective sleep quality assessed by a 100-mm visual analog scale.	Night 1 at 760 m and Night 1 at 3600 m
Subjective sleep quality	MCP-related difference in altitude-induced change in subjective sleep quality assessed by a 100-mm visual analog scale.	Night 1 at 760 m and Night 2 at 3600 m
Nocturnal oxygen saturation (SpO2)	MCP-related difference in altitude-induced change in the mean nocturnal oxygen saturation measured by pulse oximetry.	Night 1 at 760 m and Night 2 at 3600 m

Collaborators and Investigators

• Sponsor: University of Zurich
• Collaborators: University Hospital Heidelberg; National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov; Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
• Investigators: Study Chair: Michael Furian, Prof. Dr., University of Zurich; Study Director: Talant Sooronbaev, Prof. Dr., National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan

Study record dates

Study Major Dates

• Study Start (Actual): July 15, 2024
• Primary Completion (Actual): August 31, 2025
• Study Completion (Actual): August 31, 2025

Study Registration Dates

• First Submitted: July 5, 2024
• First Submitted That Met QC Criteria: July 5, 2024
• First Posted (Actual): July 12, 2024

Study Record Updates

• Last Update Posted (Actual): June 5, 2026
• Last Update Submitted That Met QC Criteria: June 3, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Women; Acetazolamide; Prevention; Hypoxia; Altitude; Periodic breathing
• Additional Relevant MeSH Terms: Nervous System Diseases; Respiratory Tract Diseases; Respiration Disorders; Sleep Wake Disorders; Signs and Symptoms, Respiratory; Apnea; Sleep Disorders, Intrinsic; Dyssomnias; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hypoxia; Sleep Apnea Syndromes
• Other Study ID Numbers: HighCycle_SDB_MCP

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No