Circadian Rhythm DisruptionDELIGHT-PNCT07791472
DElirium and LIGHT: Exploring Modifiable Risk Factors of Delirium - a Pilot Study
An observational study of Circadian Rhythm Disruption and Delirium, run by King's College Hospital NHS Trust at 1 site in United Kingdom.
Trial summary
After a period of critical illness many people develop problems with memory, attention and thinking and this can make daily life more difficult. A risk factor for these problems is delirium. Delirium is a sudden change in the brain that causes confusion and difficulty focusing. Read more about this study
- Who is it for?
- Ages 50 years and older
- Conditions the study is for
- Circadian Rhythm Disruption, Delirium
- How many people
- 10 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- Aug 2026to May 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 50 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients in critical care
Who may be able to join
- Adult patients >50 years old
- Patients admitted to critical care in previous 24 hours
- Patients with an arterial or venous access line suitable for blood sampling
- Patients with an expected length of stay >36 hours
Who cannot join
- Patients with a primary neurosurgical diagnosis
- Patients with pre-existing cognitive impairment
- Patients expected to die within 24 hours or receiving end of life treatment
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United Kingdom1 site, 1 recruiting
- Recruiting
King's College Hospital NHS Foundation Trust
London
Sean Harrington, +442032999000, sean.harrington@kcl.ac.uk
About this study
After a period of critical illness many people develop problems with memory, attention and thinking and this can make daily life more difficult. A risk factor for these problems is delirium. Delirium is a sudden change in the brain that causes confusion and difficulty focusing. People develop delirium when they are sick for another reason, such as a severe infection, or after surgery. Other risk factors for delirium are altered sleep/wake cycle, and absence of daylight. While delirium is very common in critical care, it's difficult to recognise and the reasons why it happens are not fully understood.
There are no treatments for delirium. Management focusses on reducing the impact of things that make it more likely for someone to develop delirium. For example, by making sure pain is well controlled and that family members can visit. While it comes with its challenges, maintaining a normal day and night cycle by turning lights off and reducing the number of interruptions during nighttime hours is also a strategy used and research has shown that sometimes this works. Unfortunately, the findings are not the same in every study, and the reasons why these interventions work to reduce delirium are not explored.
Read more
This study, called DELIGHT-P, wants to look at the relationship between delirium and light exposure to help to understand why absence of daylight is a risk factor for delirium. We think it has something to do with changes in the 'body clock' of patients in critical care. To find this out we will collect blood samples, measure light levels at the bedside, and assess participants for delirium. After discharge from critical care we will see participants again and ask them about their memory and do some thinking tests. We will also do another blood test. The blood samples will be tested for markers of changes to the 'body clock' and others will be tested for proteins that might be useful for recognising when someone has delirium.
As this is a pilot study, the research will be done with fewer people taking part. This is to check that the things we want to measure are the right things, and that it's possible to do the research. We hope that in the future we can do a larger study to be able to draw conclusions about what we find. The findings from this study may help us understand how light exposure and an altered body clock contributes to developing delirium. By checking for proteins that might be present in patients who have delirium, it might help us understand what processes are happening in the body to cause delirium. It is possible that through this work, we can identify potential treatment targets for delirium.
We hope that by doing this, we may be able to improve some of the memory and thinking problems that people have after a stay in critical care.
Read the detailed description
Background:
Delirium is a neuropsychiatric syndrome characterised by acute deficits in attention and other aspects of cognition. Patients with delirium have altered arousal, often displaying signs of hypervigilance and agitation, or indeed reduced levels of consciousness that look like coma. Many experience troubling symptoms in the form of hallucinations or delusions. Delirium is associated with longer hospital stays, increased mortality and long term cognitive impairment.
Delirium is highly prevalent in acute hospital environments. In critical care, it is reported that up to 70% of patients have delirium. Despite this, the mechanisms underpinning its onset and persistence are poorly understood. Recent evidence suggests that disruption in circadian rhythms - through altered light exposure, noise and sleep disturbance - may play a role in it's pathophysiology. There have been few studies which have directly measured light intensity and quality within clinical settings and correlated this to markers of circadian disruption and explored how this interacts with delirium risk.
In recent years, markers of neuronal damage have shown promise in helping to detect delirium, and understand the pathophysiological mechanisms underpinning it, but more work is needed to explore their use in critically ill patients at risk of delirium.
DELIGHT-P (DElirium and LIGHT: Exploring modifiable risk factors and mechanisms of delirium - A Pilot Study) is a pilot for a prospective observational cohort study. This observational cohort study will describe patterns of light exposure, endocrine rhythms, and delirium incidence in critically ill patients.
Results from this programme of work will inform the design of a powered observational study and potentially future studies examining whether circadian based interventions can reduce delirium incidence and improve outcomes. Beyond the critical care environment, the findings will support specialties across the NHS where delirium is highly prevalent, as well as guide hospital and critical care design, informing evidence-based policies on light exposure and sleep promoting care.
Importantly, findings from this work may also elucidate some of the mechanisms of delirium, offering insight to what is currently a very challenging syndrome with significant consequences.
Primary Objective:
To assess the feasibility of carrying out a study that exploring modifiable risk factors of delirium. To do this we will assess the recruitment capability, retention rate and evaluate the data collection procedures.
Secondary Objectives
- To explore the relationship between light exposure, altered circadian rhythms and delirium in critically ill patients.
- To explore the association between serum markers of inflammation, neuronal damage and delirium
- To explore the cognitive outcomes of critically ill patients and the relationship with markers of neuronal damage.
- Conditions
- Circadian Rhythm Disruption, Delirium
- Medical subject headings
- Delirium
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Patients in critical care | Patients receiving care in critical care |
What is being measured
The primary outcome is the main question the study is designed to answer.
Recruitment and retention
Measured: 6 months
Adherence to study procedures
Measured: 6 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Aug 2026
- Study startAug 2026 (estimated)
- Primary completionFeb 2027 (estimated)
- Study completionMay 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Circadian Rhythm DisruptionStudies of the same condition, open and under way.
- More trials run by King's College Hospital NHS TrustThe 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
- 10 participants (estimated)
Sponsor and investigators
- Lead sponsor
- King's College Hospital NHS Trust
- Sponsor type
- University, hospital or other
- Collaborators
- King's College London
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07791472
- Sponsor's protocol ID
- KCH26-023
- Other IDs
- 367559
- Acronym
- DELIGHT-P
- Status last verified
- Aug 2026
- First submitted
- 24 Aug 2026
- Last updated
- 28 Aug 2026
- Results posted
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 28 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- DElirium and LIGHT: Exploring Modifiable Risk Factors of Delirium - a Pilot Study
- ClinicalTrials.gov ID
- NCT07791472
- Acronym / sponsor ID
- DELIGHT-P / KCH26-023
- Conditions
- Circadian Rhythm Disruption, Delirium
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 10 participants (estimated)
- Lead sponsor
- King's College Hospital NHS TrustUniversity, hospital or other
- Collaborators
- King's College London
- Study start
- Aug 2026 (estimated)
- Primary completion
- Feb 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 28 Aug 2026 (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.
After a period of critical illness many people develop problems with memory, attention and thinking and this can make daily life more difficult. A risk factor for these problems is delirium. Delirium is a sudden change in the brain that causes confusion and difficulty focusing. People develop delirium when they are sick for another reason, such as a severe infection, or after surgery. Other risk factors for delirium are altered sleep/wake cycle, and absence of daylight. While delirium is very common in critical care, it's difficult to recognise and the reasons why it happens are not fully understood.
There are no treatments for delirium. Management focusses on reducing the impact of things that make it more likely for someone to develop delirium. For example, by making sure pain is well controlled and that family members can visit. While it comes with its challenges, maintaining a normal day and night cycle by turning lights off and reducing the number of interruptions during nighttime hours is also a strategy used and research has shown that sometimes this works. Unfortunately, the findings are not the same in every study, and the reasons why these interventions work to reduce delirium are not explored.
This study, called DELIGHT-P, wants to look at the relationship between delirium and light exposure to help to understand why absence of daylight is a risk factor for delirium. We think it has something to do with changes in the 'body clock' of patients in critical care. To find this out we will collect blood samples, measure light levels at the bedside, and assess participants for delirium. After discharge from critical care we will see participants again and ask them about their memory and do some thinking tests. We will also do another blood test. The blood samples will be tested for markers of changes to the 'body clock' and others will be tested for proteins that might be useful for recognising when someone has delirium.
As this is a pilot study, the research will be done with fewer people taking part. This is to check that the things we want to measure are the right things, and that it's possible to do the research. We hope that in the future we can do a larger study to be able to draw conclusions about what we find. The findings from this study may help us understand how light exposure and an altered body clock contributes to developing delirium. By checking for proteins that might be present in patients who have delirium, it might help us understand what processes are happening in the body to cause delirium. It is possible that through this work, we can identify potential treatment targets for delirium.
We hope that by doing this, we may be able to improve some of the memory and thinking problems that people have after a stay in critical care.
Detailed description
Background:
Delirium is a neuropsychiatric syndrome characterised by acute deficits in attention and other aspects of cognition. Patients with delirium have altered arousal, often displaying signs of hypervigilance and agitation, or indeed reduced levels of consciousness that look like coma. Many experience troubling symptoms in the form of hallucinations or delusions. Delirium is associated with longer hospital stays, increased mortality and long term cognitive impairment.
Delirium is highly prevalent in acute hospital environments. In critical care, it is reported that up to 70% of patients have delirium. Despite this, the mechanisms underpinning its onset and persistence are poorly understood. Recent evidence suggests that disruption in circadian rhythms - through altered light exposure, noise and sleep disturbance - may play a role in it's pathophysiology. There have been few studies which have directly measured light intensity and quality within clinical settings and correlated this to markers of circadian disruption and explored how this interacts with delirium risk.
In recent years, markers of neuronal damage have shown promise in helping to detect delirium, and understand the pathophysiological mechanisms underpinning it, but more work is needed to explore their use in critically ill patients at risk of delirium.
DELIGHT-P (DElirium and LIGHT: Exploring modifiable risk factors and mechanisms of delirium - A Pilot Study) is a pilot for a prospective observational cohort study. This observational cohort study will describe patterns of light exposure, endocrine rhythms, and delirium incidence in critically ill patients.
Results from this programme of work will inform the design of a powered observational study and potentially future studies examining whether circadian based interventions can reduce delirium incidence and improve outcomes. Beyond the critical care environment, the findings will support specialties across the NHS where delirium is highly prevalent, as well as guide hospital and critical care design, informing evidence-based policies on light exposure and sleep promoting care.
Importantly, findings from this work may also elucidate some of the mechanisms of delirium, offering insight to what is currently a very challenging syndrome with significant consequences.
Primary Objective:
To assess the feasibility of carrying out a study that exploring modifiable risk factors of delirium. To do this we will assess the recruitment capability, retention rate and evaluate the data collection procedures.
Secondary Objectives
- To explore the relationship between light exposure, altered circadian rhythms and delirium in critically ill patients.
- To explore the association between serum markers of inflammation, neuronal damage and delirium
- To explore the cognitive outcomes of critically ill patients and the relationship with markers of neuronal damage.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Patients in critical care | – | –Patients receiving care in critical care |
Who may qualify
- Ages
- 50 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients in critical care
Key inclusion criteria (4 listed)
- Adult patients >50 years old
- Patients admitted to critical care in previous 24 hours
- Patients with an arterial or venous access line suitable for blood sampling
- Patients with an expected length of stay >36 hours
Key exclusion criteria (3 listed)
- Patients with a primary neurosurgical diagnosis
- Patients with pre-existing cognitive impairment
- Patients expected to die within 24 hours or receiving end of life treatment
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Recruitment and retention
Time frame: 6 months
Adherence to study procedures
Time frame: 6 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Aug 2026.
- Individual participant dataSharing planned: No
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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.
King's College Hospital NHS Foundation Trust
London, United Kingdom
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 Circadian Rhythm Disruption and Delirium, run by King's College Hospital NHS Trust at 1 site in United Kingdom.
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 4 inclusion and 3 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: looking for participants now, as of the sponsor's last update on 28 Aug 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 United Kingdom. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Recruitment and retention (time frame: 6 months). The study lists 2 primary outcomes in all. 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 28 Aug 2026.