Poor sleep quality during the first night in the ICU—especially reduced sleep time and increased wake after sleep onset—may be linked to the development of delirium.
Delirium occurred in 19.3% of ICU patients during their stay, with 9.3% screening positive on the second day and 14.9% on the third day.
Shorter sleep time on the first night was statistically significantly associated with delirium on the second day of ICU stay.
A higher wake after sleep onset (WASO) ratio on the first night was statistically significantly associated with delirium on the second day.
Delirium on the third day was strongly associated with the presence of delirium on the second day rather than sleep parameters from the preceding night.
The study used a prospective observational design with wearable device-based objective sleep measurement across multiple ICUs.
This research suggests that the quality of sleep during a patient's first night in the intensive care unit (ICU) is linked to whether they develop delirium—a state of acute confusion—the following day. Specifically, patients who slept for shorter total durations and spent more time awake after initially falling asleep were more likely to develop delirium on day two of their ICU stay. The study tracked 357 patients across six ICUs in South Korea, using a Fitbit Sense smartwatch to objectively measure sleep and a standardized tool (CAM-ICU) to assess delirium. Overall, about 1 in 5 patients (19.3%) developed delirium at some point during their ICU stay. By day three, delirium was more strongly predicted by whether the patient already had delirium on day two and by the overall severity of their illness, rather than by their sleep the night before. This suggests that once delirium takes hold, it tends to persist and becomes harder to separate from other illness factors. This research suggests that nurses and ICU care teams could potentially reduce delirium risk by paying close attention to patients' sleep from the very first night and implementing early interventions to support normal sleep-wake cycles. Practical strategies might include minimizing nighttime disruptions, managing lighting and noise, and considering non-pharmacological approaches to improve sleep. Since delirium in the ICU is associated with longer hospital stays, cognitive decline, and other serious outcomes, identifying modifiable risk factors like sleep quality is clinically meaningful.
Kang J, Cho H, Kim S, Jeong J. (2026). Sleep Quality and Delirium Occurrence in Intensive Care Unit Patients: A Prospective Observational Study.. Nursing in critical care. https://doi.org/10.1111/nicc.70435