Sleep-Disordered BreathingNCT06498544
HighCycle Study: Effect of High Altitude on Sleep Disordered Breathing in Women Related to Their Menstrual Cycle Phase
An observational study of Sleep-Disordered Breathing, run by University of Zurich at 1 site in Kyrgyzstan.
Trial summary
Prospective cohort study investigating the menstrual cycle phase (MCP) dependent sleep disordered breathing (SDB) in women travelling to 3600 m. Read more about this study
- Who is it for?
- Ages 18 to 44 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Sleep-Disordered Breathing
- What is being tested?
- Exposure to 3600 m
- How many people
- 91 participants
- Where
- 1 siteKyrgyzstan
- Study dates
- 15 Jul 2024to 31 Aug 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 44 years
- Women only
- Healthy volunteers accepted
- Adult
Study population: Healthy, non-smoking, premenopausal women, age 18-44 years, without any disease and need of regular medication (including oral contraceptives).
Who may be able to join
None listed.
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
Kyrgyzstan1 site
National Center for Cardiology and Internal Medicine
Bishkek, Bishkek, 720040
About this study
Official 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.
Prospective cohort study investigating the menstrual cycle phase (MCP) dependent sleep disordered breathing (SDB) in women travelling to 3600 m.
- Conditions
- Sleep-Disordered Breathing
- Being tested
- Exposure to 3600 m
- Keywords
- Periodic breathing, Hypoxia, Prevention, Acetazolamide, Women, Altitude
- Medical subject headings
- Sleep Apnea Syndromes, Hypoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Exposure to 3600 mOther
Participants will travel to and stay for 2 nights at an altitude of 3600 m.
| Study group | Role | What they receive |
|---|---|---|
| Women in luteal MCP | Women being in their luteal MCP on the day of ascent to high altitude. Receives: Other: Exposure to 3600 m | |
| Women in follicular MCP | Women being in their follicular MCP on the day of ascent to high altitude. Receives: Other: Exposure to 3600 m |
What is being measured
The primary outcome is the main question the study is designed to answer.
Nocturnal oxygen saturation (SpO2)
MCP-related difference in altitude-induced change in the mean nocturnal oxygen saturation measured by pulse oximetry.
Measured: Night 1 at 760 m and Night 1 at 3600 m
Secondary outcomes (7)
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).
Measured: 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).
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Night 1 at 760 m and Night 2 at 3600 m
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Jul 2024
- Study start15 Jul 2024
- Primary completion31 Aug 2025
- Study completion31 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Sleep-Disordered BreathingStudies of the same condition, open and under way.
- More trials run by University of ZurichThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 91 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Zurich
- Sponsor type
- University, hospital or other
- Collaborators
- National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov, University Hospital Heidelberg, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
- Responsible party
- Sponsor
- Investigators
- Michael Furian, Prof. Dr., Study chair, University of ZurichTalant Sooronbaev, Prof. Dr., Study director, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06498544
- Sponsor's protocol ID
- HighCycle_SDB_MCP
- Status last verified
- Jun 2026
- First submitted
- 5 Jul 2024
- Last updated
- 5 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 5 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official 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.
- ClinicalTrials.gov ID
- NCT06498544
- Acronym / sponsor ID
- HighCycle_SDB_MCP
- Conditions
- Sleep-Disordered Breathing
- Keywords
- Periodic breathing, Hypoxia, Prevention, Acetazolamide, Women, Altitude
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 91 participants (actual)
- Lead sponsor
- University of ZurichUniversity, hospital or other
- Collaborators
- National Center of Cardiology and Internal Medicine named after academician M.Mirrakhimov, University Hospital Heidelberg, Laboratoire des Adaptations Métaboliques à l'Exercice en conditions Physiologiques et Pathologiques
- Study start
- 15 Jul 2024 (actual)
- Primary completion
- 31 Aug 2025 (actual)
- Study completion
- 31 Aug 2025 (actual)
- First posted
- 12 Jul 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Prospective cohort study investigating the menstrual cycle phase (MCP) dependent sleep disordered breathing (SDB) in women travelling to 3600 m.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Women in luteal MCP | – | Other: Exposure to 3600 mWomen being in their luteal MCP on the day of ascent to high altitude. |
| Women in follicular MCP | – | Other: Exposure to 3600 mWomen being in their follicular MCP on the day of ascent to high altitude. |
Who may qualify
- Ages
- 18 to 44 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Healthy, non-smoking, premenopausal women, age 18-44 years, without any disease and need of regular medication (including oral contraceptives).
Key inclusion criteria (0 listed)
Key exclusion criteria (5 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Exposure to 3600 mParticipants will travel to and stay for 2 nights at an altitude of 3600 m. | Other | Women in follicular MCP, Women in luteal MCP |
Primary outcome
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.
7 secondary outcomes
Nocturnal oxygen desaturation index (ODI)
Time frame: Night 1 at 760 m and Night 1 at 3600 m
Nocturnal oxygen desaturation index (ODI)
Time frame: Night 1 at 760 m and Night 2 at 3600 m
Apnea/hypopnea index (AHI)
Time frame: Night 1 at 760 m and Night 1 at 3600 m
Apnea/hypopnea index (AHI)
Time frame: Night 1 at 760 m and Night 2 at 3600 m
Subjective sleep quality
Time frame: Night 1 at 760 m and Night 1 at 3600 m
Subjective sleep quality
Time frame: Night 1 at 760 m and Night 2 at 3600 m
Nocturnal oxygen saturation (SpO2)
Time frame: Night 1 at 760 m and Night 2 at 3600 m
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Jun 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Michael Furian, Prof. Dr. study chair
University of Zurich
Talant Sooronbaev, Prof. Dr. study director
National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Sleep-Disordered Breathing, run by University of Zurich at 1 site in Kyrgyzstan.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 0 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 5 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Kyrgyzstan. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Nocturnal oxygen saturation (SpO2) (time frame: Night 1 at 760 m and Night 1 at 3600 m). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Jun 2026.