Administering a placebo to patients with insomnia disorder may worsen sleep disturbances on the first sleep lab night, with no significant differences in the duration and percentage of N1, N2, N3 and REM, according to study results published in Sleep Medicine.
The goal of the current study was to explore the effect of placebo administration on the first-night effect in patients with insomnia disorder.
The study cohort included 36 patients with insomnia disorder who were requested to avoid any changes in their lifestyle habits throughout the study. Of these, 16 were in the placebo (PL) group (mean age, 39.75 years; 62.50% women) and 20 were in the drug-free (DF) group (mean age, 39.90; 50.0% women). The patients reported a usual bedtime between 9 pm and 1 am and time in bed of >7 hours during the previous 3 months. All participants underwent 2 consecutive nights of polysomnography (PSG) in the study laboratory and recorded sleep diaries for 1 week at home before the sleep lab study.
The data suggested that placebo administration in patients with insomnia disorder may worsen sleep with increased sleep onset latency, wake after sleep onset (WASO), and time in bed, and decreased sleep efficiency on the first sleep lab night compared to the DF group. In the PL group, the self-reported total sleep time on the first night was reduced and WASO was increased compared with the second night. However, there were no differences between the groups in the duration and percentage of N1, N2, N3 and REM, nor with respect to the difference between the 2 consecutive nights of PSG data.
The study had several limitations, including the retrospective design, potential effect of increased anxiety on results, and the fact that the inclusion criterion did not clarify that participants should have had no previous PSG.
“[T]he results,” the researchers explained, “emphasize the importance of patients’ perception of and belief in insomnia and suggest that in some cases, short-term use of a placebo may result in nocebo responses.”
Hu S, Chen J, Li Y, et al. The influence of placebo administration on the first- night effect in patients with insomnia disorder]. Sleep Med. 2020;72:138-143.