Sleep and biorhythm in the ICU

Background of the study:

Metabolic disturbances associated with critical illness may disturb secretion of melatonin, the most important factor for
circadian timekeeping. This disturbance may in turn hamper distribution and high quality sleep, with potentially
detrimental effects on patient cognition and behaviour.

Objective of the study:

To investigate the incidence and severity of disturbed biorhythm among ICU patients, and the effect on quality of sleep.
We also aim to validate the novel ICU Depth Of Sleep (IDOS) index in detecting depth of sleep over time. Secondarily: we
will determine the incidence, duration and severity of disturbed sleep and delirium among ICU patients.

Study design:

Prospective observational pilot study

Study population:

50 adult ICU patients with an expected stay of >48 hours in the ICU of the UMCG.

Primary study parameters/outcome of the study:
Correlation between sleep continuity and amplitude of melatonin secretion

Interrater agreement between methods of sleep analysis (defined by Cohen’s Kappa):

o R&K analysis and IDOS index

o Somnolyzer score and IDOS index

o Actigraphy and IDOS index

Sleeprelated
parameters (using EEG: Rechtschaffen & Kales (R&K) manual scoring, and IDOS method):

o total sleep time (any sleep stage other than awake, EEG)

o number of awakenings and arousals

o sleep efficiency

o sleep continuity

Biorhythm:

o time and amplitude of concentration of melatonin secretion

o minimum melatonin concentration

o difference between peak and minimum

Secundary study parameters/outcome of the study (if applicable):

Cognitive and behavioural parameters:

o ICU delirium by CAMICU

o ICU delirium manifestation type defined by RASSscores65
(hypo/hyperactive, or mixed)

o duration of ICU delirium

o clinical requirement for pharmacological intervention (haloperidol)

Environmental parameters:

o light levels (lux)

o light frequencies

o noise levels (decibel), and number of peaks exceeding 65dB

o temperature (degrees Celsius)

ICU and hospital length of stay

Mortality (until ICU discharge, hospital discharge, 6 and 12 months after hospital discharge)

Amount of administered opioids, benzodiazepines, sedatives and antipsychotics

Nature and extent of the burden and risks associated with participation, benefit and group relatedness (if
applicable):

There is no foreseeable risk involved with participation in this observational pilot study. The greater majority of ICU
patients undergo frequent blood withdrawal from indwelling catheters for routine measurements. Participation in this
study will marginally increase the total amount of blood taken, while also utilizing irregularly sampled blood from routine
measurements. This additional material provides more data without increasing the burden on ICU patients.

Metabolic disturbances associated with critical illness may disturb secretion of melatonin, the most important factor for
circadian timekeeping. This disturbance may in turn hamper distribution and high quality sleep, with potentially
detrimental effects on patient cognition and behaviour.

24 hours after admission to the ICU, with a maximum inclusion duration of 72 hours.

- none