Sleep in the ICU and Hospital: Why It Is So Difficult and How to Improve It

Why Sleep Is So Poor in the ICU

Multiple studies using polysomnography in ICU patients have documented complete disruption of normal sleep architecture. Research published in Critical Care Medicine identified seven major categories of ICU sleep disruption:

• Environmental noise: ICUs average 60 to 70 decibels, similar to busy traffic, with peaks exceeding 80 dB from alarms, equipment, and staff conversation
• Continuous light: Most ICUs maintain bright lighting around the clock, suppressing melatonin production
• Care interventions: Patients are disturbed for monitoring, medication, turning, and assessment up to 40 times per 24 hours
• Mechanical ventilation: Patient-ventilator asynchrony and respiratory discomfort directly interrupt sleep
• Sedative and analgesic medications: Many ICU drugs alter sleep architecture, increasing N2 sleep while abolishing slow-wave and REM sleep
• Pain and discomfort: Persistent pain elevates cortisol and prevents sleep continuity
• Psychological stress: Fear, disorientation, and ICU delirium create a state of hyperarousal incompatible with restorative sleep

Sleep on a Ventilator

Mechanically ventilated patients face unique sleep challenges. The ventilator breath pattern must synchronise with the patient's own respiratory effort. When it does not (patient-ventilator asynchrony), the resulting discomfort triggers arousals and prevents sleep consolidation. Modern ICUs use adaptive ventilation modes that better match patient effort, and sedation protocols are increasingly being designed to preserve some natural sleep architecture rather than simply inducing unconsciousness.

For conscious ventilated patients (such as those on non-invasive ventilation for COPD or sleep apnoea), the key comfort factors are proper mask fit, appropriate pressure settings, and adequate humidification. Heated humidification significantly improves comfort and compliance.

ICU Delirium and Sleep

ICU delirium (acute brain dysfunction characterised by confusion, agitation, and altered consciousness) affects 20 to 80% of ICU patients and is both caused by and causes further sleep disruption. The ABCDEF bundle (Assess pain, Both SAT and SBT, Choice of analgesia, Delirium monitoring, Early mobility, Family engagement) used in progressive ICUs includes sleep promotion as a core component. Early mobility and family presence during the day significantly reduce delirium incidence.

What Families Can Do

Family members visiting ICU patients can actively contribute to sleep improvement. Advocating for ear plugs, eye masks, and clustering of care activities to allow uninterrupted 90-minute periods is appropriate and increasingly supported by ICU nursing protocols. Speaking quietly, maintaining a calm presence, and avoiding overstimulation during nighttime visits supports the patient's natural sleep drive. Bringing familiar small items such as a pillow from home can reduce the disorienting effect of the ICU environment.

Post-ICU Sleep Problems

Post-intensive care syndrome (PICS) affects up to 50% of ICU survivors and includes persistent insomnia, nightmares, and PTSD-related sleep disruption that can last months to years after discharge. Early psychological support and CBT-I have the strongest evidence base for post-ICU insomnia. Families should watch for these symptoms and advocate for referral to a sleep or psychiatric service when they persist.