'Lavender after trepanation': Aromatherapy improves sleep and reduces delirium in patients with brain tumors

A randomized controlled trial published in Frontiers in Pharmacology found that inhalation of lavender essential oil via nighttime nasal patches for the first 7 days after brain surgery improved objective sleep parameters and reduced the duration of postoperative delirium. On day 4, the lavender group had longer (~29 minutes longer on average) and deeper sleep (N3 ~28 minutes longer), and fell asleep faster; anxiety decreased by day 7. No serious adverse events were noted.

Background

• Why sleep is key after brain surgery. Surgery and hospital stays often result in shortened sleep, sleep fragmentation, and a reduced proportion of deep sleep (N3/REM). These disruptions are associated with poorer recovery, higher rates of cognitive problems, and a greater risk of delirium.
• Delirium after craniotomy is not uncommon. Meta-analyses suggest that delirium occurs in approximately 12–26% of patients after intracranial surgery; its risk is increased by pain, poor night sleep, and sensory stressors of the department.
• Sleep ↔ delirium: a two-way relationship. Systematic reviews show that pre- and postoperative sleep disturbances increase the chances of delirium and postoperative cognitive dysfunction; in patients undergoing brain surgery, poor preoperative sleep increases the risk of delirium several-fold. Hence the idea of targeted sleep improvement as a preventive measure against PND.
• Why not reach for sleeping pills straight away. Pharmacological sedatives (especially benzodiazepines) may themselves worsen confusion in vulnerable patients; therefore, there is increased interest in non-pharmacological and “gentle” methods of improving sleep in the early postoperative period. (This thesis is supported by directions in reviews on postoperative sleep and delirium.)
• What is known about lavender before this study. Lavender essential oil is one of the most studied aromatherapy agents: in meta-analyses in adults, it has been shown to moderately improve subjective sleep quality and in some studies, reduce anxiety; however, many trials were small and did not include objective polysomnography. The biologically plausible mechanism is associated with the linalool/linalyl acetate components, which, when inhaled, affect GABAergic and other systems, reducing sympathetic activity.
• What was missing and what the current work closes. In neurosurgery, there were almost no randomized trials with objective sleep recording in the first days after surgery. The current RCT is testing nightly lavender inhalations in patients after craniotomy, assessing sleep with wearable sensors and, in parallel, the frequency and duration of delirium. This fills the gap between the "general" work on aromatherapy and the specific vulnerable population of neurosurgery.

What did they do?

In Beijing, 42 adult patients scheduled for elective craniotomy for intracerebral tumors were recruited and randomly assigned to:

• LEO group: five drops of 10% lavender oil on a cotton pad of a nasal patch, fixed at the nasolabial fold every night from 20:00 to 08:00 for 7 days;
• control: without additional procedure.

Sleep was measured objectively — with a continuous wearable monitor (PPG + accelerometer + temperature sensors), and cognitive impairment was assessed using CAM-ICU (delirium) and MMSE (telephone screening after 1 and 3 months). Anxiety and depression — using HADS. The chemical composition of the oil was tested using GC-MS: linalyl acetate (34.5%) and linalool (27.9%) predominated — they are most often associated with a sedative-anxylytic effect.

Key Results

• Sleep on the 4th day:
  • Total sleep duration: 418.5 ± 22 min versus 389.6 ± 49 min in the control (p = 0.019).
  • Deep sleep (N3): 95.1 ± 20 min vs. 66.9 ± 32.7 (p = 0.002).
• Architecture and falling asleep (average over 7 days):
  • Sleep latency was shorter: 13.2 ± 8.5 min vs. 28.6 ± 19.9 (p = 0.002).
  • Apnea-hypopnea (AHI) is lower: 14.1 ± 9.9 vs. 21.0 ± 10.8/h (p = 0.035).
  • Fewer awakenings: 2.67 ± 1.32 vs. 5.05 ± 2.97 per night (p = 0.002).
• Neurocognitive outcomes:
  • Delirium lasted less: 2.0 ± 0.82 days versus 3.8 ± 1.3 (p = 0.048).
  • Anxiety (HADS-A) on the 7th day is lower: 3.38 ± 2.27 versus 6.14 ± 5.43 (p = 0.038).
  • In a subanalysis, women experienced greater anxiolytic and hypnotic effects (exploratory result).

Why is this important?

After neurosurgery, many patients suffer from insomnia and sleep fragmentation due to pain, room noise, nocturnal manipulations, anxiety, and medications. Poor sleep, in turn, increases the risk of delirium, slows recovery, and prolongs hospitalization. A simple nonpharmacologic intervention that improves objective sleep metrics and reduces delirium is a rare blessing. Lavender oil has long been studied for anxiety and insomnia, but there is little data specifically after brain surgery and with objective sleep monitoring.

How it can work

The main components of lavender, linalyl acetate and linalool, enter the bloodstream when inhaled and affect the GABAergic and other neurotransmitter systems of the limbic region. In practice, this results in a decrease in sympathetic activity, easier falling asleep, and more stable “deep” sleep; improved sleep, in turn, reduces neuroinflammation and the risk of delirium.

What is alarming (restrictions)

• No placebo/"sham" control. The control group was "nothing", i.e. it was impossible to blind the patients by smell. The effect of some indicators may include expectation/ritual.
• Small sample, single center. 42 patients is a starting scale; confirmation is needed in different clinics and on more heterogeneous cohorts.
• The peak of significance is on the 4th day. The remaining nights showed a "trend", but without strict statistics - perhaps the effect is cumulative and does not appear immediately.
• Objective, but not the "gold standard." Used a validated wearable monitor rather than polysomnography; this is a limitation for making fine-grained inferences about sleep stages.

What's next?

The authors call for large placebo-controlled studies (e.g. with neutral odor) and assessment of the impact on “hard” outcomes – length of hospital stay, complications, readmissions. A practical idea right now: in patients with brain tumors, it is reasonable to test safe sensory interventions (noise hygiene, light, aromatherapy) as part of standard care in the first nights after surgery.

Source: Liu Y. et al. Effects of lavender essential oil inhalation aromatherapy on postoperative sleep quality in patients with intracranial tumors: a randomized controlled trial. Frontiers in Pharmacology, August 4, 2025. Registry ID: ChiCTR2300073091. https://doi.org/10.3389/fphar.2025.1584998