Table 1.

Sleep assessment methods

Sleep assessment tool	Validated against PSG	Description	Ratings done by	Advantages	Disadvantages
May also have utility in evaluating sleep during delirium
Polysomnography (PSG) [53, 79, 80, 82, 83]		Multimodal tool involving electroencephalography (EEG), electrooculography (EOG), electromyography (EMG), respiratory effort, oxygen saturation, and electrocardiography	Data analyzed by computers in real time, confirmed by experts	Gold standard to sleep/wake and sleep stage evaluation in non-critically ill patients Objective Can aid in diagnosis of sleep disorders	Cumbersome, costly, resource intensive, and prone to dislodgement in hospitalized or critically ill patients Vulnerable to misinterpretation in hospitalized patients
EEG [84, 85]	Yes	Utilizes numerous scalp leads to measure brain activity; does not include EMG, EOG	Data analyzed by computers in real time, confirmed by experts	High sensitivity and specificity for sleep-wake determination Objective	Interpretation in critically ill patients challenging due to factors (i.e., sedatives) which can affect the EEG pattern Lacks specificity in sleep stage differentiation
Odds ratio product (ORP) [86, 87]	Yes	EEG-derived continuous estimate of sleep depth, ranging from 0 (deep sleep) to 2.5 (fully awake)		Validated in ambulatory patients	Same interpretation challenges of EEG interpretation
Actigraphy [89–93]	Yes	Accelerometer-based device (often a wristwatch) which measures patient activity	Activity data analyzed by computer algorithm, used to determine sleep-wake	Surrogate for sleep-wake measurement in community settings Noninvasive	Overestimation of “sleep” in mostly inactive hospitalized and/or critically ill patients
Do not have utility in evaluating sleep during delirium
Richards-Campbell Sleep Questionnaire (RCSQ) [94–97]	Yes	Subjective assessment involving 100 mm visual analogue scale to assess 5 domains of sleep: depth, latency, efficiency, quality, and number of awakenings	Proxies can complete if patients are unable	Brief Easy to administer Inexpensive Can be administered repeatedly	Infeasible in cognitively impaired (e.g., delirious) patients Nurse proxies may overestimate patients’ sleep quality
Leeds Sleep Evaluation Questionnaire (LSEQ) [99]	No	Subjective assessment involving 10,100 mm visual analogue scales related to falling asleep, sleep quality, awakenings, daytime alertness, feelings, and balance	Completed by patients	Brief Easy to administer Inexpensive	Infeasible in cognitively impaired (e.g., delirious) patients Not validated against PSG
Verran/Snyder-Halpern Sleep Scale [98]	No	Subjective assessment of sleep over the previous three nights, two visual analogue scales evaluating sleep: disturbance and effectiveness	Completed by patients	Takes longer time to complete than RCSQ	Infeasible in cognitively impaired (e.g., delirious) patients Validated for ages 20–78 years with no history of sleep difficulties
Sleep in Intensive Care Unit Questionnaire (SICUQ) [54]	No	Subjective 27-item evaluation of sleep quality at home and the ICU environment, on Likert scales of 1–10, with questions about disruptiveness of ICU activities and noises	Completed by patients	Compares subjective assessment of sleep in ICU and at home	Infeasible in cognitively impaired (e.g., delirious) patients Does not account for severity of illness or medication use
Saint Mary’s Hospital Sleep Questionnaires (SMHSQ) [100]	No	Subjective 14-item evaluation of sleep in the hospital	Completed by patients	Designed for repeated use	Takes longer to complete Low internal consistency

PSG polysomnography, EEG electroencephalography, EOG electrooculography, EMG electromyography, ORP odds ratio product, RCSQ Richards-Campbell Sleep Questionnaire, LSEQ Leeds Sleep Evaluation Questionnaire, VSH Verran/Snyder-Halpern Sleep Scale, SICUQ Sleep in Intensive Care Unit Questionnaire, SMHSQ Saint Mary’s Hospital Sleep Questionnaires