Table 2. Research questions according to PICO criteria.

Population	Interventions	Comparators	Outcomes
Adults diagnosed with chronic insomnia	Table 1	No treatment	Sleep latency (PSG or actigraphy)
Adults with moderate to severe insomnia symptoms		Waiting list	Total sleep time (PSG or actigraphy)
		Placebo	Sleep efficiency (PSG or actigraphy)
		Minimum intervention	WASO (PSG or actigraphy)
		Pharmacotherapy*	Sleep quality (PSQI)
		CBT-I (any format) *	Daytime sleepiness (ESS)
			Insomnia symptoms (ISI)
			Insomnia diagnosis
			Sleep diary*
			Self-reported total sleep time, sleep latency, and sleep efficiency*

Abbreviations: CBT-I, Cognitive-behavioral therapy applied to insomnia; ESS, Epworth Sleepiness Scale; ISI, Insomnia Severity Index; PICO, Population, intervention, comparator, and outcome; PSG, Polysomnography; PSQI, Pittsburgh Sleep Quality Index; WASO, wake after sleep onset.

^*Items applied only to search strategies related to non-pharmacological interventions.