Does total sleep time substantially increase after cognitive behavioral therapy for insomnia?

The findings of the current study indicate that the reported average of an approximately 45-minute gain in self-reported TST after CBT-I is not modal, or common, across patients. At post treatment, most participants’ TST was not appreciably higher than baseline levels (83%). While TST increases in a linear fashion in the 24 months following treatment discontinuation, a substantial proportion of participants (> 36.5%) do not appreciably increase their sleep duration (by ≥ 30 minutes). Additionally, participants who eventually increased TST by an appreciable duration did not experience these improvements until 3, 6, and up to 12 months after treatment. Therefore, the original finding that TST increases after 6–8 sessions of CBT-I is more nuanced than first appears.

It is known that large gains in SL and WASO can be achieved with CBT-I,with an approximately 45-minute increase in TST seeming to naturally emerge by 6 months following treatment. The current study elucidates the latter finding, indicating that a reasonable proportion of patients do not experience substantial gains in TST. Examining the changes in 15-minute increments at each time point indicated that there was considerable variability in TST gains after CBT-I, especially at later time points (6-, 12-, and 24-months follow-up). Patients who appreciably increased their TST after CBT-I appeared to be upwardly titrating their sleep opportunity, since the increases in TST occurred without increases in SL, WASO, and EMA. Notably, the gains with this approach were slow, since appreciable changes in TST did not seem to arise until 3–6 months after CBT-I. In addition, these gains in TST occurred without improvements in the ISI. This may be because the first 3 items of the ISI relate to sleep continuity disturbance (and none of the items assess sleep duration). Thus, changes on the ISI were unlikely to occur when SL, WASO, and EMA remained stable. Regardless, a considerable proportion of patients do not appreciably increase TST above the 5.5–6 hours per night reported at pre-treatment.

https://jcsm.aasm.org/doi/10.5664/jcsm.10004