Table 1.

Studies Evaluating OSD In CBT-I

Study	Population	Methods To Assess OSD	Type Of CBT-I Treatment	Results
Troxel et al. (2013)38	N = 39 (age: 72.54 ± 6.61)	Actigraphy record; PSG baseline recording	Three weeks of Brief Behavioral Treatment for Insomnia (BBTI)	Longer SL at the baseline: more likely to respond to BBTI SSD group: less remission of insomnia at the follow-up No evidence for an effect of overall delta activity or slope of delta activity across the night
Lovato et al. (2016)51	N = 91 (age: 63.34 ± 6.41) 39 SSD 52 NSD	PSG baseline recording	Four weeks of group CBT-I sessions	No differences in treatment outcomes between the two sleep duration groups
Bathgate et al. (2017)36	N = 60 (age: 56.2 ±10.1) 35 SSD 25 NSD	Actigraphy record	Eight weeks of individual CBT-I sessions	SSD group: Less remission of insomnia symptoms Lower improvements in SE and TWT More difficulty to fall asleep after awake during the night No significant changes in post-treatment TST
Miller et al. (2018)37	N = 96 (age: 41.4 ± 11.8) 43 SSD 53 NSD	PSG baseline recording	Different treatment modalities: Digital CBT only Face-to-face CBT only Digital CBT + face-to-face CBT Sleep Restriction Therapy only Sleep Restriction Therapy + face-to-face CBT Sleep Restriction Therapy + digital CBT	SSD group showed less response to CBT-I
Crönlein et al. (2018)52	N = 92 39 SSD (age: 53.0±11.7) 53 NSD (age 49.2±11.4)	PSG baseline recording	Two weeks of group CBT-I sessions	No group difference in the primary outcomes
Rochefort et al. (2019)53	N = 159 (age: 50.31 ± 10.14) 51 SSD 108 NSD	PSG baseline recording	Two treatment modalities: Eight week of CBT-I sessions Eight week of CBT-I sessions + Zolpidem	OSD did not moderate treatment response to either CBT-I or CBT-I+Zolpidem

Abbreviations: OSD, objective sleep duration; BBTI, brief behavioural treatment of insomnia; SSD, short sleep duration; NSD, normal sleep duration; SE, sleep efficiency; TWT, total wake time; TST, total sleep time; PSG, polysomnography.