The influence of environmental factors on sleep quality in hospitalized medical patients

Abstract

Introduction: Sleep-wake disturbances are common in hospitalized patients but few studies have assessed them systematically. The aim of the present study was to assess sleep quality in a group of medical inpatients, in relation to environmental factors, and the switch to daylight-saving time.

Methods: Between March and April 2013, 118 consecutive inpatients were screened and 99 (76 ± 11 years; hospitalization: 8 ± 7 days) enrolled. They slept in double or quadruple rooms, facing South/South-East, and were qualified as sleeping near/far from the window. They underwent daily sleep assessment by standard questionnaires/diaries. Illuminance was measured by a luxmeter at each patient's eye-level, four times per day. Noise was measured at the same times by a phonometer. Information was recorded on room lighting, position of the rolling shutters and number/type of extra people in the room.

Results: Compliance with sleep-wake assessment was poor, with a range of completion of 2-59%, depending on the questionnaires. Reported sleep quality was sufficient and sleep timing dictated by hospital routine; 33% of the patients reported one/more sleepless nights. Illuminance was generally low, and rolling shutters half-way down for most of the 24 h. Patients who slept near the window were exposed to more light in the morning (i.e., 222 ± 72 vs. 174 ± 85 lux, p < 0.05 before the switch; 198 ± 72 vs. 141 ± 137 lux, p < 0.01 after the switch) and tended to sleep better (7.3 ± 1.8 vs. 5.8 ± 2.4 on a 1-10 scale, before the switch, p < 0.05; 7.7 ± 2.3 vs. 6.6 ± 1.8, n.s. after the switch). Noise levels were higher than recommended for care units but substantially comparable across times/room types. No significant differences were observed in sleep parameters before/after the switch.

Conclusion: Medical wards appear to be noisy environments, in which limited attention is paid to light/dark hygiene. An association was observed between sleep quality and bed position/light exposure, which is worthy of further study.

Keywords: circadian rhythms; hospital; internal medicine; light; noise; sleep.

Figure 1

Relationship between average rolling shutter position (1 = up, 0.5 = half-way, 0 = down) and average, recorded illuminance at patients’ eye level in slot 1, between 7:30 and 8:30 in the morning. r = 0.27, p < 0.05; broken gray lines: 95% Confidence Intervals.

Figure 2

Subjective sleep quality (0 = worst, 10 = best) in patients, classified based on the position of their bed in relation to the window (far or near). Small black square: mean; box: ±SE; whisker: ±1.96 SD. *p < 0.05.