Table 1.

Summary of the studies included within the review that investigated a conservative technique to improve the sleep of patients in ICU.

Publication	No. of subjects	Sex	Mean age (years)	Setting	Population	Intubated	Room type	Sleep measures	Environmental intervention	Objective environmental measurements	Intervention duration	Outcomes
Dennis et al.20	50 (35 day + 15 night)	19 M 16 F + 6 M 9 F	55.5 + 52.9	Neuro ICU	Neurological	None	Around core station	Nursing assessments (Sleep Observation Tool)	Quiet Time protocol twice daily 01:30–03:30 and 14:00–16:00	Noise reduced by 9.0 dB (day) and 1.4 (night) Light reduced 142.6 lux (day) and 9.8 (night)	6 months	Significantly more likely to sleep during the quiet time periods in afternoon, but not night
Foreman et al.21	6 vs 6 controls	5 M 1 F vs. 4 M 2 F	59 vs. 56	Neuro ICU	Neurological	7/12	–	Polysomnography	Eyemasks, noise-cancelling headphones, and melatonin	Not recorded	<7 nights	Difficulty assessing sleep from PSG due to large number of records unscorable No difference in groups between night 1 and 3
Hu et al.22	14	6 M 8 F	31.1	Simulated ICU	Healthy	None	–	Polysomnography Sleep diary Sleep visual analogue scale	Eyemasks and earplugs	N/A	1 night	Increased REM sleep and reduced REM latency and arousals Improved subjective sleep quality
Hu et al.23	20 vs. 25 controls	11 M 9 F vs. 16 M 9 F	56.6 vs. 56.8	Cardiac surgery ICU	Post cardiac surgery	Average duration for population 22–23 h	–	Richards-Campbell sleep questionnaire	Eyemasks, earplugs, and relaxing music at night and in the morning (30 min) vs. routine care	No difference in light/sound levels between groups (monitored 20:00 to 08:00)	2 nights on ICU	Improved sleep scores on all sleep scales
Huang et al.24	Four groups of 10	50% M vs. 40% M vs. 50% M vs. 60% M	40.1 vs. 42.0 vs. 39.7 vs. 52.8	Simulated ICU	Healthy	None	Private rooms	Polysomnography Sleep visual analogue scale	Eyemasks and earplugs vs. melatonin vs. placebo vs. control	N/A	4 nights	Intervention reduced sleep latency, arousals, and awakenings
Jones and Dawson25	50 vs. 50 controls	30 M, 20 F vs. 27 M, 23 F	56.3 vs. 58.1	ICU	Medical and surgical	None	Varied	Likert scales for sleep quantity and quality Factors facilitating and preventing sleep	Eyemasks and earplugs vs. routine care	Not recorded	ICU admission	Increased sleep duration but not sleep quality (no statistical analysis)
Kamdar et al.26	178 vs. 122 control	7% M 93% F vs. 46% M 54% F	54 vs. 54	Medical ICU	Medical	47% vs. 64% (during stay)	Private	Richards-Campbell sleep questionnaire (<45% completed by nurses) Sleep in the ICU questionnaire (abbreviated)	Sleep promoting intervention (multiple approaches in three additive stages with staff training and daily checklists) vs. routine care	Not recorded	≥1 night	No significant difference in sleep quality ratings Reduced incidence of delirium
Li et al.27	28 vs. 27 controls	57% M 43% F vs. 78% M 22% F	49.3 vs. 50.7	Surgical ICU	Post-surgery	None	–	Richards-Campbell sleep questionnaire Sleep in the ICU questionnaire	Sleep care guidelines (changing nursing regimes and reducing noise/light at night with staff education course) vs. routine care	Peak and average noise significantly reduced Mean peak noise 51.3 vs. 59.2 dB (bed) Mean noise 50.1 vs. 57.7 dB (bed)	3 months	Increased sleep quality and efficiency
Olson et al.28	121 vs. 118 controls	53% M 47% F vs. 52% M 48% F	51 vs. 48	Neuro ICU	Neurology and neurosurgery	–	–	Nurse assessments	Quiet time protocol twice daily 02:00–04:00 and 14:00–16:00	Significant reduction in noise/light during day/night	2 months	1.6 times more likely to be observed sleeping Significantly more likely to be asleep during afternoon period only
Patel et al.29	Subgroup: 29 vs. 30 controls	55% M 45% F vs. 47% M 53% F	60.5 vs. 61.9	ICU	Medical and surgical	–	–	Richards-Campbell sleep questionnaire Sleep in the ICU questionnaire	Care bundle (reducing sleep disturbance, noise, and light with staff training and champions, patients offered eyemasks/earplugs) vs. routine care	Nocturnal measures: Mean noise 61.8 vs. 68.8 dB Mean light 301 vs. 594 lux Interactions 23.4 vs. 33.6 Awoken by interactions 9.0 vs. 11.0	1 month	Increased sleep quality, efficiency, and reduced sleep during the day. Significantly more time asleep at night (8.6 h vs. 6.6) Lower incidence of delirium
Richardson et al.30	34 vs. 28 controls	69% M 31% F	18+	Cardiothoracic ICU	Cardiothoracic	None	Cubicle and open bay	Likert scales for sleep quantity and quality Factors facilitating and preventing sleep	Eyemasks and earplugs vs. routine care	Not recorded	ICU admission	Increased sleep duration quality compared to normal sleep (no statistical analysis)
Ryu et al.31	29 vs. 29 controls	19 M 10 F vs. 19 M 10 F	61.2	Cardiac ICU	Coronary angiography	None	–	Verran and Snyder-Halpern sleep scale Quantity of sleeping questionnaire	Eyemasks, earplugs, and sleep-inducing music (52 min) vs. eyemasks and earplugs	Not recorded	1 night	Increased subjective sleep quantity and quality
Scotto et al.32	49 vs. 39 controls	55% M 45% F vs. 67% M 33% F	63.7 vs. 62.5	Critical care	Medical and few surgical	None	–	Verran and Snyder-Halpern sleep scale	Earplugs vs. routine care	Not recorded	1 night	Increased scores on sleep scales with exception of satisfaction falling asleep
Van Rompaey et al.33	69 vs. 67 controls	68% M 32% F vs. 64% M 36% F	57 vs. 62	ICU	Medical and surgical	None	Separated spaces/rooms	Dichotomous sleep questions	Earplugs vs. routine care	Not recorded	<4 nights	Improved sleep scores on night one (earplugs decreased risk of confusion/delirium by 53%)
Wallace et al.34	6	100% M	25	Simulated ICU	Healthy	None	–	Polysomnography Subjective sleep duration	Earplugs	N/A	1 night	Intervention reduced REM sleep latency and increased REM sleep duration

Study patient demographics, settings, interventions, and outcome measures of the 15 studies included in the review.

ICU: intensive care unit.