Table 1 Description of intervention arms: HABITs and HABITs + Texts

Sessions 1–3

Three 50-min sessions, consisting of ^a :

- Sleep diary review

- Sleep and circadian science. For example:

o Regularizing bed and wake times

o Devising a rise-up routine

o Devising a wind-down routine

o Reducing sleep related worry/anxiety (i.e., relax the mind strategies)

o Improving sleep efficiency (i.e., stimulus control and sleep restriction)

o Improving daytime functioning

- Habit science. For example:

o Identifying contextual cues, the importance of repetition, and identifying rewards

o Dismantle unhelpful habits by identifying contextual cues, rewards, and methods (i.e., substitution, removing or curtailing the activity, or re-organizing the activity)

- Case conceptualization with script elicitation to derive habit bundle(s)

o Typically, 1–2 bundles (i.e., primary and secondary; for examples, see Table 2)

- Motivational enhancement

- Home projects

Sessions 4–9

Six 30-min sessions, consisting of ^a :

- Reviewing and refining sleep habit bundle(s)

- Assessing progress and obstacles

- Sleep and circadian science

- Habit science

- Reinforcing contextual cues and motivations

- Maintenance and relapse education

No text messaging

Six weeks of text messaging, consisting of:

- Cues

- Self-monitoring

- Rewards