A few drops of this Japanese tree oil may help you sleep more soundly

A Japanese cypress root oil may help people wake less at night, fall into deeper sleep more smoothly, and feel more refreshed in the morning.

Sleep difficulties are especially common during middle age, including among women in their 40s and 50s. New research suggests that an aromatic oil made from the roots of Hinoki (Chamaecyparis obtusa), also known as Japanese cypress, could offer a simple way to support better sleep at home.

In a study published September 1, 2026, in the Journal of Wood Science, researchers tested Hinoki root essential oil and found several encouraging signs. Participants experienced fewer awakenings during the night, reported feeling better in the morning, and showed brain wave patterns associated with a smoother transition into sleep.

Hinoki is an important timber tree in Japan, but its roots are often left behind and unused after logging. Those roots contain fragrant compounds that can be extracted to make essential oils.

Scientists have previously investigated oils produced from Hinoki leaves and branches, but oils derived specifically from the roots have received far less attention.

"We wanted to address two questions: whether essential oil production could add value to underused Hinoki roots and whether that oil could improve sleep," says Associate Professor Kuniyoshi Shimizu from Kyushu University's Faculty of Agriculture. "In our earlier work, we examined sleep quality over a single day in a laboratory-like setting. However, sleep is strongly influenced by daily routines and the home environment. Therefore, we decided to examine the effect of repeated use over two weeks in participants' own bedrooms using both subjective assessments and physiological measurements."

The study involved 12 Japanese women between the ages of 35 and 60. Using a single blind crossover design, every participant spent two weeks using Hinoki root essential oil and another two weeks using an unscented control.

Before going to sleep, the women placed three drops of oil into a paper cup and breathed in the scent for 10 seconds. They then positioned the cup about 30 cm from their noses and left it there overnight.

Researchers tracked sleep in several ways. Participants wore a headband that recorded brain waves, used a smartwatch to monitor sleep, and filled out a questionnaire each morning about how they had slept and how they felt upon waking.

Repeated exposure to the Hinoki root aroma was associated with improvements across several measures of sleep.

By the 13th day of using the oil, participants said they felt less sleepy after waking and more recovered from fatigue compared with periods when they used the unscented control. Data from their smartwatches also indicated that they woke up fewer times during the night.

The brain wave recordings revealed another potentially important change. After seven days of using the Hinoki oil, participants showed increased delta wave activity around the time they were falling asleep. This pattern is consistent with a smoother progression into deeper stages of sleep.