25. Lighting: Characteristics of included studies.

Study ID	Methods	Participants	Interventions	Outcomes	Notes
Walch 2005	CCT; 2 parallel groups.	DESCRIPTION: 89 post‐operative in‐patients recovering from elective cervical and lumbar spinal surgeries in single patient rooms, Pittsburgh, USA. NUMBERS: Bright room = 44, Dim room = 45. AGE, mean (SD): Bright room = 60.1 (13.7), Dim room = 57.6 (13.4) years old. GENDER (male/female): Bright room = 25/19, Dim room = 18/27. ETHNICITY (Caucasian/other): Bright room = 42/2, Dim room = 40/5. INCLUSION CRITERIA: undergoing elective cervical and lumbar spinal surgery. Admitted to single‐occupancy room. EXCLUSION CRITERIA: Discharge on day after surgery; history of major depression or use of antidepressant medications.	BRIGHT ROOM: On west side of the corridor. Received approximately 46% more natural sunlight than dim rooms (received on average 73,537 lux‐hours per day). DIM ROOM: On east side of the corridor. The light to these rooms was blocked due to an adjacent building approximately 25 meters away (received on average 50,410 lux‐hours per day). Rooms were of the same configuration and size. No attempt was made to control patient usage of window blinds and room lighting.	ANALGESIC CONSUMPTION: obtained via chart extraction and standardised to morphine equivalent mg/hr. PAIN: Recorded on post‐operative day one and on the day of discharge via McGill Pain Questionnaire. On discharge those in the bright rooms reported less pain although this was not significant (P value = 0.058). DEPRESSION: The Centre for Epidemiological Studies Depression Scale on first and last post‐operative day. There were no differences between groups. ANXIETY: Measured using the POMS anxiety scale on first and last post‐operative day. There were no differences between groups. STRESS: Measured using the Perceived Stress Scale on first and last post‐operative day. Patients in the bright rooms reported significantly less stress on day of discharge (P value = 0.035).	Analgesic consumption data extracted for entire LOS mg/hr.

POMS: Profile of Mood States