Does Sleep Affect Response to Exposure Therapy?

I know what you’re thinking, “just what the world needs, another article about the importance of sleep”. Sleep is essential for memory consolidation so it should surprise no one that improving sleep should improve outcomes of psychotherapy (which rely on learning). However, deciding which psychotherapeutic ingredients to package together from the bounty on offer, and in what order, provides many clinicians with a dilemma, so I’m always interested when researchers test drive a new combination. Christopher Hunt and colleagues (2023) report on how 40 Veterans with comorbid PTSD and insomnia did in the Prolonged Exposure (PE) plus Cognitive Behaviour Therapy for Insomnia (CBTi) arm of a larger randomised controlled trial. Their protocol (see Figure below) combined 5 sessions of CBTi and 8 sessions of PE, where psychoeducation about PE was included in the first 2 sessions of CBTi. The purpose of this study was to explore the temporal relationships between sleep, PTSD symptoms and fear extinction (as indicated by reductions in peak distress during exposure exercises) using cross-lagged panel models.

Sleep efficiency improved substantially during the CBTi phase, from 72% to 83%, accompanied by significant reductions on the Insomnia Severity Index, and remained between 83 to 89% throughout the PE phase. Participants achieved some reduction in PTSD symptoms during the CBTi phase with twice as much further improvement during the PE phase.

Interestingly, they found that participants with higher sleep efficiency (and less Waking time After Sleep Onset) for a given week (calculated from sleep diaries) experienced lower peak distress during imaginal exposure exercises the following week. In contrast, peak distress during exposure and PTSD symptoms did not predict sleep efficiency during the following week. The improvements in PTSD symptoms and fear extinction were not predicted by total sleep time.

The authors tentatively concluded that improved sleep efficiency might facilitate extinction learning, however, their confidence that this was due to sleep-facilitated improvements in memory consolidation was limited by: a) the effect of sleep efficiency on PTSD symptoms was largely independent from (and not mediated by) the effect of sleep efficiency on fear extinction; and b) fear extinction was also predicted by shorter sleep onset latency which theoretically, is not likely to affect memory consolidation. The authors also considered that improved sleep efficiency might simply be tapping into better treatment adherence which was then associated with response to PE. Although the study doesn’t conclusively demonstrate that improving sleep improves memory consolidation and therefore psychotherapy, it demonstrates how these dual diagnoses can be efficiently addressed without significantly compromising the effects on either problem.

Clinician implications

  • Routinely assess for insomnia in some detail.

    • Screening questionnaires such as the Insomnia Severity Index or Pittsburgh Sleep Quality Inventory could be part of an intake packet for a bare minimum passive check.

    • A decent sleep assessment should include the timing and stability of timing of: time to bed; sleep onset; final wake-up time; final get-up time; number of awakenings and time awake. Better quality information would be obtained by sleep diaries but an initial screening of these parameters can take place in interviews to determine the pay-off for sleep diary assessment

  • When faced with probable insomnia/dysregulated sleep comorbid with emotional disorders, encourage clients to prioritise stabilising sleep as a treatment target ahead of other tasks.

  • Promote empirically supported behaviour changes to sleep:

    • Ask client to choose a regular achievable wake-up time and set alarm.

    • Restrict time in bed to the average sleep achieved according to baseline sleep diaries; this means if a 2-week monitoring phase shows the client achieves 6.25 hours on average and on average can wake up at 6:30am, tell the client not to go to bed until at least 12:15am.

    • Teach the client the difference between sleepiness and feeling fatigued (but not sleepy). Ask clients to delay going to bed until sleepy (and then, after the planned minimum time to bed – e.g., 12:15am in this example).

    • Maintain as much stimulus control over the bed environment: avoid activities other than sleep in bed and avoiding sleeping outside the bed.

    • Maximise how conducive the bedroom environment is to sleeping, especially re light, noise and temperature.

    • Continue sleep diaries while implementing behaviour changes and monitor for sleep efficiency = time asleep / time in bed. Aim for 85-90% sleep efficiency. Also monitor daily sleepiness and fatigue. Once 85-90% sleep efficiency is achieved, if sleepiness persists, increase sleep opportunity by allowing time to bed earlier, by 15 or 30 minute increments (depending on severity).

For more information, see Perlis, Jungquist, Smith & Posner (2008). Cognitive Behavior Treatment of Insomnia: A Session-By-Session Guide.

For the original article, go to: https://www.sciencedirect.com/science/article/pii/S0165178123001671?via%3Dihub

REFERENCES


Hunt, C., Park, J., Bomyea, J., & Colvonen, P. J. (2023). Sleep efficiency predicts improvements in fear extinction and PTSD symptoms during prolonged exposure for veterans with comorbid insomnia. Psychiatry Research, 324, 115216–115216. https://doi.org/10.1016/j.psychres.2023.115216

Matthew Smout