The SleepCARE trial tested whether cognitive behavior therapy for insomnia (CBT-I) and bright light therapy (BLT) reduce insomnia and fatigue symptoms in women having chemotherapy for breast cancer. It also tested whether combining the two works better than either alone. No prior RCT had compared CBT-I and BLT head to head, or tested them together, during active chemotherapy.

WHAT WAS FOUND

219 women were randomized to CBT-I, BLT, CBT-I plus BLT, or sleep hygiene education (SHE), all groups over 6 weeks.

Insomnia: CBT-I groups improved significantly more than non-CBT-I groups (ISI score down 2.19 points more, P = .002). BLT did not beat non-BLT groups on insomnia.

Fatigue: Neither CBT-I nor BLT beat the comparison groups on fatigue. All four groups, including SHE, showed within-group fatigue improvement.

Follow-up: The CBT-I advantage on insomnia partly reversed during the 6-month follow-up period. No group kept improving after treatment ended.

Subgroups: In women with metastatic breast cancer, BLT (unlike in the full sample) significantly improved both insomnia and fatigue. Women with more severe baseline insomnia responded best to CBT-I. Women with mild baseline symptoms showed little benefit from any treatment.

Safety: No serious treatment-related adverse events. BLT had more mild adverse events (headache, dizziness) than CBT-I.

IMPORTANCE OF THIS RESEARCH

Insomnia affects roughly 62% of women with breast cancer and rises to about 70% during chemotherapy. Fatigue affects around 43%. Both are linked to worse quality of life, and insomnia and fatigue are each associated with shorter survival and higher recurrence risk. CBT-I is the established first-line insomnia treatment, but most of the evidence for it comes from after cancer treatment ends, not during chemotherapy, when patients are already stretched thin. BLT targets circadian rhythm disruption, a plausible mechanism for both insomnia and fatigue during chemo, but past BLT trials were small and rarely compared to an active alternative. With chemotherapy regimens getting longer, finding a treatment that is brief, scalable, and effective during active treatment matters for a large number of patients.

SIMILAR WORK DONE IN THE PAST

This trial builds directly on the SleepWell trial (Bean et al, 2022), a smaller single-center RCT testing CBT-I plus BLT combined against usual care. SleepCARE deliberately harmonized its measures with SleepWell so it could compare data across the two trials. In that combined analysis, every SleepCARE group (except SHE) beat SleepWell’s usual-care group on insomnia, and the CBT-I plus BLT group beat usual care on fatigue too. This supports the idea that even brief, low-intensity versions of these interventions can outperform standard care.

SIMILAR PAST WORK THAT CONFLICTS WITH RESEARCH

Several earlier BLT trials (Ancoli-Israel 2012, Jeste 2013, Rissling 2022) reported that light therapy prevented fatigue worsening or improved sleep during chemotherapy. SleepCARE did not replicate this in its full sample. The authors suggest a possible reason: light delivered at wake time mainly shifts the circadian clock earlier, which helps people with delayed rhythms but may not help everyone equally. This is also the first trial to formally test CBT-I and BLT together for an interaction effect, and it found none. That’s a meaningful contrast to the assumption that combining mechanistically different treatments should add up to something better.

STRONG POINTS OF THIS RESEARCH

• 2×2 factorial design lets you isolate CBT-I effects, BLT effects, and their interaction in one trial, which is efficient and rare in this literature.
• Adequately powered (Monte Carlo simulation, ~210 target, achieved 219) with prespecified clinical significance thresholds rather than just statistical significance.
• Latent growth modeling with full information maximum likelihood handles missing data more rigorously than simple endpoint comparisons.
• Multicenter (5 sites, metro and regional), improving generalizability within Australia.
• Multiple prespecified subgroup analyses (adherence, baseline severity, cancer stage) add nuance rather than treating the sample as homogeneous.
• Cross-trial comparison with SleepWell strengthens the case that all four SleepCARE arms may be more effective than doing nothing, even without a passive control in this trial itself.
• Adverse events tracked systematically, supporting a genuine safety read rather than an afterthought.

LIMIATIONS OF THIS WORK

• No true no-treatment or passive control arm. Every group got an active-ish intervention (SHE plus contact with a therapist), so within-group improvement in all arms could reflect therapeutic alliance, natural recovery, or regression to the mean rather than genuine SHE efficacy.
• Unblinded design. This is unavoidable for behavioral interventions but means expectancy and contact-time differences (CBT-I sessions ran much longer than SHE sessions) could partly drive the CBT-I advantage.
• No objective sleep measures. Everything is self-report (ISI, PROMIS-Fatigue). No actigraphy or polysomnography to confirm subjective improvement matches physiological change.
• Substantial and uneven dropout, highest in the combined CBT-I plus BLT arm (26.9%), which both threatens internal validity and undercuts the additive-effects hypothesis that the combined arm was supposed to test.
• No objective adherence data for BLT (light glasses were self-reported), so BLT’s null result could partly reflect under-dosing rather than true inefficacy.
• The metastatic subgroup finding for BLT is exploratory and based on a small sample. It’s hypothesis-generating, not confirmatory.
• Fixed light timing protocol (morning-focused) doesn’t account for individual circadian phase typing, which the authors themselves flag as a likely reason for the null BLT result.
• Generalizability limited to English-fluent women in Australia, and the findings can’t be extended to men or other cancer types.

CLINICAL APPLICATION / UTILITY

For most women on chemotherapy for breast cancer, brief CBT-I looks like a reasonable first-line option for treating insomnia symptoms, even fairly early in treatment. A single intensive consultation plus email follow-up was enough to produce clinically meaningful ISI improvement, which is encouraging for scalability in busy oncology settings that can’t offer multi-session in-person CBT-I.

BLT does not look justified as a default insomnia or fatigue treatment for the general chemotherapy population based on this trial. But the signal in women with metastatic disease is worth flagging to clinicians managing that subgroup, with the caveat that it needs confirmation in a dedicated trial before it changes practice.

Combining CBT-I and BLT doesn’t appear to add benefit and comes with higher dropout, so stacking interventions on top of an already burdened chemotherapy patient may not be worth the extra load. Clinicians should also expect a rebound in insomnia symptoms after CBT-I ends, so some plan for booster contact or relapse prevention seems worth considering. Finally, treating women who already have low symptom burden appears to have little value, arguing against blanket preventive rollout and for targeting these interventions at patients who report at least mild insomnia or fatigue.

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Do TT, Maccora J, Wallace R, et al. Cognitive behavior vs bright light therapy for insomnia in women undergoing chemotherapy for breast cancer: a randomized clinical trial. JAMA Netw Open. 2026;9(8):e2630320. doi:10.1001/jamanetworkopen.2026.30320