An observational study in Circadian Rhythm Disruption and Delirium, sponsored by King's College Hospital NHS Trust. Recruiting at 1 site in United Kingdom. Open to participants aged 50 Years and older. Per ClinicalTrials.gov, last updated 2026-08-28.
Sponsored by King's College Hospital NHS Trust · Observational
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.
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
933 studies on the registry are indexed under Delirium; 190 are open to participants now.
This study's planned enrollment of 10 is below the median of 194 across 342 observational studies indexed under Delirium.
Browse Delirium studies →King's College Hospital NHS Trust is the lead sponsor of 171 studies on the registry; 56 are open to participants now.
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Adult patients in critical care
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Exclusion Criteria:
Patients receiving care in critical care
Recruitment and retention
Time frame: 6 months
Adherence to study procedures
Time frame: 6 months
Plan to share: No
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