Sleep Disorders: Clinical Trials

What is a clinical trial?

A clinical trial, also called a research study, tests the value and safety of various interventions in people. Clinical trials are meant to find new and improved methods of evaluating or treating a condition or it can test a new way to prevent diseases. Such trials can involve risks, and there is no guarantee regarding the outcome of a trial. Clinical trials are conducted in phases and may span long periods of time.

Phases of a clinical trial

  • In a Phase I clinical trial, a new treatment is given to a small number of participants. The researchers determine the best way to give the new treatment and how much of it can be given safely. These trials have a limited number of participants who would not be helped by other known treatments or alternatively, a phase I trial is performed in healthy volunteers to determine the safety of a particular treatment.
  • Phase II clinical trials focus on learning whether the new treatment has an effect on a specific condition. Additional information regarding the side effects of the treatment is also obtained. A small number of people are included because of the risks and unknowns involved.
  • Phase III clinical trials compare the new treatment with the standard treatment. In this phase, researchers determine which study group has fewer side effects and is undergoing the most improvement.
  • Phase IV clinical trials, also called post-marketing studies, are conducted after a treatment has been approved. The purpose of these trials is to provide an opportunity to learn more details about the treatment and to address questions that may have come up during the other phases.

Terms you need to know

Clinical trial participants are assigned at random (a process similar to flipping a coin) to either the new treatment (treatment group) or the current standard treatment (control group). Randomization helps to avoid bias (having the study's results affected by human choices or other factors not related to the treatments being tested). When no standard treatment exists for a condition, some studies compare a new treatment with a placebo (a look-alike pill/infusion that contains no active drug). However, a person is told this is a possibility before deciding whether or not to take part in a study.

What happens in a clinical trial?

In a clinical trial, patients receive treatment and researchers observe how the treatment affects patients. The patient's progress is closely monitored during the trial. Once the treatment portion of the trial has been completed, researchers may continue to follow patients in order to gather more information about a treatment’s effects.

Risks involved in clinical trials

While clinical trials have risks for the people who take part, each study also takes steps to protect patients. Only an individual can decide whether taking part in a clinical trial is worthwhile. The possible benefits and risks should be considered carefully.

Questions you should ask your referring physician about the clinical trial:

  • What is the purpose of the study?
  • What has previous research of this treatment shown?
  • What is likely to happen in my case with or without the treatment?
  • Are there standard treatments for this condition?
  • How does this study compare with standard treatment options?

You can learn more

For the most current listing of clinical trials in the field of sleep disorders, please consult the Web site and conduct a search under the term "sleep disorders. The National Sleep Foundation Clinical Trials Resource Center also has information about specific clinical trials concerning sleep disorders. Contact this site at

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition.This document was last reviewed on: 2/10/2005