AuthorisedTherapeutic exploratory (Phase II)Interventional

SUNCET: Low sodium oxybate Use for Nocturnal Cluster headache: safety, Efficacy and Tolerability of XYWAV - a Phase 2 Randomized, Double-Blind, Placebo-Controlled, bi-center Study

Cluster headaches are extremely painful headaches that often wake people up in the middle of the night. This clinical trial is testing a liquid medicine known as low sodium oxybate (XYWAV) to see if it can safely reduce the number of nighttime attacks. Adults aged 18 and older with cluster headaches can take part. Half of the participants will receive the real medicine, and half will receive a dummy liquid (placebo). Neither the participants nor the study doctors will know who is taking which treatment during the test. Participants will take the liquid medicine at night for a four-week stable treatment period. Throughout the trial, you will track your headaches in a diary. The main aim is to see if people taking the study medicine have fewer nighttime attacks and less pain compared to those taking the placebo.

At a glance

Status

Authorised

Phase

Therapeutic exploratory (Phase II)

Sponsor

Leids Universitair Medisch Centrum (LUMC)

Enrolment target

Start

13 Jul 2026

Cluster headache

What is this study about?

Cluster headaches are severe, intensely painful headaches that strike quickly, often around one eye. They frequently happen at night, waking people from deep sleep and making it very difficult to get good rest. Because these nighttime attacks can be so distressing and hard to control, researchers are looking for new treatments to help people sleep through the night without pain.

This trial is testing a medicine called low sodium oxybate. It is a liquid taken by mouth at bedtime that may help regulate brain signals and sleep patterns. Doctors want to find out whether taking this medicine every night can lower the number of headache attacks people experience between going to bed and getting up in the morning.

The study is a Phase 2 clinical trial, which means researchers are checking how well the medicine works and monitoring any side effects. Participants are randomly put into two groups: one group receives the active medicine, while the other receives an identical-looking dummy treatment called a placebo. Comparing the two groups allows researchers to see if any improvements are truly due to the medicine.

Key takeaways

Tests a bedtime liquid medicine (low sodium oxybate) for nighttime cluster headaches.
Open to adults aged 18 and over who get cluster headaches during sleep.
Half of the participants will receive the real medicine and half will receive a dummy treatment (placebo).
Involves taking the medicine at night and tracking your headaches for at least four weeks.
Joining is completely voluntary and you can withdraw whenever you choose.

Who may be eligible?

This trial is open to adults aged 18 and older who suffer from cluster headaches. Because the study focuses specifically on nighttime pain, participants should be people who regularly experience headache attacks during the night or while trying to sleep.

Both men and women may join. Before entering the study, the research team will review your medical history, your current medications, and your overall health to make sure the trial is safe for you.

You may not be eligible if you have certain other medical or sleep conditions, or if you take specific medicines that cannot be mixed with the trial drug. The study team will discuss these details with you during your initial screening.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged 18 or older.
I have been diagnosed with cluster headaches.
My cluster headaches often wake me up or happen during the night.
I am willing to take a bedtime liquid medicine every night for a month.
I am able to keep a daily diary of my headache attacks.

Answer every question to see your result.

What does participation involve?

Taking part in the trial involves several steps over a few months. First, you will attend a screening visit where doctors check your health and confirm if the trial is right for you. You will also complete a baseline period where you track your usual headache patterns.

During the main part of the study, you will take an oral liquid medicine each night before bed for a four-week treatment period. You will be asked to keep a daily headache diary to record when attacks happen, how severe the pain is, and how long they last. You will attend regular check-ups at the study clinic or have phone consultations so the medical team can monitor your safety, run routine health checks, and see how you are feeling.

Potential risks and benefits

You may experience fewer nighttime headaches during the trial, but there is no guarantee the treatment will help your symptoms. Your participation will also help doctors learn more about treating cluster headaches in the future. There is a risk of side effects from the study medicine, which the research team will explain in detail. Because this is a placebo-controlled trial, you might receive a dummy treatment that contains no active medicine. Taking part is completely voluntary, and you are free to leave the trial at any time without it affecting your regular NHS medical care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Netherlands

Common questions

What is a cluster headache?

A cluster headache is a rare, severe type of headache. It causes sharp, piercing pain typically on one side of the head, often around or behind the eye, and commonly strikes during the night.

What is a placebo?

A placebo is a harmless dummy treatment that looks and tastes like the real medicine but contains no active ingredients. It helps researchers prove whether the real medicine actually works.

Can I choose whether I get the real medicine or the placebo?

No. A computer randomly decides who gets the medicine and who gets the placebo. Neither you nor your study doctor will know which one you are taking during the test.

Will taking this medicine cure my cluster headaches?

The trial medicine is not a cure. The aim of this study is to see if it can reduce how often severe nighttime attacks happen and make them less painful.

What happens if I want to stop taking part?

You can leave the study at any time, for any reason. Doing so will not affect your standard NHS treatment or your relationship with your regular doctor.