Sleep pattern alteration is a core feature of bipolar disorder (BD), often challenging to treat and affecting clinical outcomes. Suvorexant, a hypnotic agent that decreases wakefulness, has shown promising results in treating primary insomnia. To date, data on its use in BD are lacking. This study evaluated the efficacy and tolerability of adjunctive suvorexant for treatment-resistant insomnia in BD patients.

Thirty-six BD outpatients (19 BDI, 69.4% female, 48.9 [±15.2] years) were randomized for 1 week to double-blind suvorexant (10–20 mg/day) versus placebo. Then, all subjects who completed the randomized phase were offered open suvorexant for 3 months. Subjective total sleep time (sTST) and objective total sleep time (oTST) were assessed.

During the randomized control trial (RCT) phase, an overall increase in the oTST emerged, which was statistically significant for the Cole–Kripke algorithm (p = 0.035). The comparison between the suvorexant and placebo groups was limited by significant differences between measurements at baseline. During the open phase, no significant improvement was detected relative to either sTST and oTST. No adverse events nor major intolerances were reported.

Efficacy results are inconsistent. During the RCT phase, only a small increase in the objective oTST emerged, while during the open phase, no significant improvement was detected. While this is the first ever study of suvorexant in BD-related insomnia, the limitation of the small sample and the high rate of dropouts limits the generalizability of these findings. Larger studies are needed to assess suvorexant in treating BD-related insomnia.

Lemborexant has demonstrated statistically significant improvements in sleep onset and sleep maintenance compared with placebo and zolpidem tartrate extended release, measured both objectively using polysomnography and subjectively using sleep diaries, in the phase 3 clinical trial SUNRISE 1. This study evaluated the cost-effectiveness of lemborexant compared with suvorexant, zolpidem immediate release (IR), and untreated insomnia.

A decision-tree model was developed for falls, motor vehicle collisions, and workplace accidents associated with insomnia and insomnia treatments from a Japanese healthcare perspective and with a 6-month time horizon. The model extracted subjective sleep onset latency treatment responses and disutility values for non-responders from SUNRISE 1. Cost-effectiveness was assessed using incremental cost per quality-adjusted life year (QALY) gained. One-way and probabilistic sensitivity analyses were conducted to evaluate the impact of parameter uncertainty on the results.

In the base-case analysis, the mean estimated QALYs for lemborexant, suvorexant, zolpidem-IR, and untreated insomnia were 0.4220, 0.4204, 0.4113, and 0.4163, and expected medical costs were JPY 34 034, JPY 38 371, JPY 38 139, and JPY 15 383, respectively. Lemborexant saved JPY 4337 and JPY 4105 compared with suvorexant or zolpidem-IR, respectively, while conferring QALY benefits. The incremental cost-effectiveness ratio (ICER) of lemborexant compared with that of untreated insomnia was JPY 3 220 975 /QALY. Lemborexant was dominant over suvorexant and zolpidem-IR and was cost-effective when compared with untreated insomnia. Sensitivity analyses supported the results' robustness.

In a Japanese clinical practice setting, lemborexant may represent a better investment for treating insomnia in the healthcare system in Japan.