Table 2.

Suggested chronobiological approaches to preserve circadian rhythms on the intensive care unit (ICU)

Zeitgeber	Ideal ICU environment
Light	• Bright-light daylight hours (> 1000 lx) • Minimise light pollution at night (< 1 lx, consider) • Eye masks at night
Feeding	• Intermittent daytime feeding aligned to usual meal times • Avoid continuous and overnight feeding
Temperature	• Warmer environment during the day and cooler at night
Exercise rehabilitation	• Similar time each day • Take patient chronotype into consideration when planning schedule
Noise	• Minimise noise during the night time • Ear plugs at night
Medical and nursing interventions	• Minimise at night and cohort together • For non-sedated patients, allow patients to sleep according to their natural schedule, rather than a staff-based schedule
Sedative drugs	• Minimise use through regular review and avoid “sleeping tablets” • Consider melatonin (up to 5 mg) at 0900 h as circadian preserving sleep aide • When possible, give drugs at the time of day least disturbing to circadian rhythms