Circadian Regulation of Sleep in Habitual Short Sleepers and Long Sleepers
Public ClinicalTrials.gov record NCT00001546. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
Routine sleep duration varies greatly among individuals. The biological meaning of this variation is unknown. The term circadian rhythm refers to the biological clock that regulates the timing of falling asleep, waking up, and secretion of hormones, like melatonin. Melatonin is secreted at night. Previous studies have shown that melatonin may play a role in the regulation of sleep. The purpose of this study is to learn whether the duration of nighttime (nocturnal) melatonin secretion is longer in people with long regular sleep duration than people with short sleep duration. Researchers will compare levels of melatonin and cortisol, body temperature, sleepiness, and sleep in two extreme groups. Group one will be made up of people with short sleep duration lasting less than 6 hours. Group two will be made up of people with long sleep duration lasting more than 9 hours.
Study identification
- NCT ID
- NCT00001546
- Recruitment status
- Completed
- Study type
- Observational
- Phase
- Not listed
- Enrollment
- 38 participants
Conditions and interventions
Conditions
Interventions
Not listed
Eligibility (public fields only)
- Age range
- Not listed
- Sex
- All
- Healthy volunteers
- Accepts healthy volunteers
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Apr 30, 1996
- Primary completion
- Not listed
- Completion
- May 31, 2000
- Last update posted
- Mar 3, 2008
1996 – 2000
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| National Institute of Mental Health (NIMH) | Bethesda | Maryland | 20892 | — |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT00001546, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Mar 3, 2008 · Synced Sep 11, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT00001546 live on ClinicalTrials.gov.