Scents derived from tea, lavender, sandalwood, and coniferous trees improve sleep quality.

Scent Effects


One of the effects of fragrance is a calming effect. The sedative effect refers to the ability to calm an irritated or agitated state. Many scents with sedative effects are said to be effective in improving sleep, such as facilitating falling asleep, because they suppress sympathetic nerve activity and make parasympathetic nerve activity dominant. And the scents of black tea, lavender, sandalwood, and coniferous trees have sedative effects.

Black tea

The research paper “紅茶の香りがストレス意識の高い女性の睡眠に及ぼす影響” is cited and referenced.

The study involved healthy women in their 30s and 40s who were stressed and dissatisfied with their sleep. Twenty subjects working at least 4 days a week for at least 3.5 hours a day were included in the study. The experimental method was to place an ultrasonic aroma diffuser at a distance of 1 m from the bedside and use it for 3 hours starting 1 hour before bedtime. The results were compared between a state in which approximately 100 ml of black tea aroma solution was volatilized and a state in which 100 ml of water was volatilized. As a result, there was an improvement in sleepiness upon waking, dreaminess, and recovery from fatigue. The latency to fall asleep (the time it takes to fall asleep) was shortened (13 minutes for the black tea aroma solution and 29 minutes for the water). This resulted in a particularly large improvement in sleep duration, with longer sleep duration and increased sleep efficiency.

The black tea aroma solution also decreased stress.

Lavender

The research paper “ラベンダーの香りがストレス負荷時の睡眠中の自律神経活動に及ぼす影響” is cited and referenced.

In this study, male students were used as subjects and were compared to a lavender fragrance inhalation group and a no fragrance group. A decrease in heart rate was observed after inhalation of lavender fragrance. In the figure below, ● indicates the group that inhaled lavender fragrance and ○ indicates the group that did not inhale lavender fragrance. In the group that inhaled the lavender fragrance, the heart eventually beat once every 1150 msec (1.15 sec), while in the group that inhaled no fragrance, the heart beat once every 1050 msec (1.05 sec). The heart rate was lower in the group that inhaled the lavender fragrance. A lower heart rate means a calmer state of mind.

In a comparison of sleep, there was an increase in sleep stage 3, which is deep sleep (33.86 minutes in the lavender fragrance inhalation group and 27.08 minutes in the no fragrance group) and an increase in sleep efficiency (93.24% in the lavender fragrance inhalation group and 89.61% in the no fragrance group), suggesting that the sleep quality was improved.

Fragrance derived from sandalwood and coniferous trees

The research paper “香りの分析と香りの効果効能について” is cited and referenced.

Sandalwood is used as the fragrance for incense offered to graves and fans in Japan. Because of its calming effect, even today it is used in Buddhist temples during meditation, and is a great aroma for those who want to improve their concentration. Cedarwood includes fragrant trees such as cedar and cypress. Coniferous trees contain a fragrant component called cedrol, which is the scent you smell when you walk in a forest or woodland and has a relaxing effect. This cedrol has the effect of suppressing the appearance of beta waves, which are brain waves that occur during arousal, and it has the effect of alleviating or eliminating excessive arousal. Cedrol is available in concentrations ranging from 0.01 ppb to 10 ppb (ppb stands for concentration and is one-tenth of a percent. Since % is one hundredth of one percent, 1% is 10 million times 1 ppb), it exerts a sedative effect in excessively sympathetic-dominant individuals. Conversely, for those who are overly parasympathetic, it has the effect of restoring them to their physiologically optimal levels. This paper contains a variety of information on the functions of fragrance, so I have included a table.

To enjoy the fragrance

General ultrasonic vibration humidification method to spread fragrance. It can be used for any fragrance. The unit automatically turns off when the water in the tank runs out, so there is no need to worry about it running dry.
Easy, all-purpose aroma diffuser

Aroma oils are available in many varieties here. Click on “Essential Oils” and you will find sandalwood and cedarwood on the first page and lavender on the second page of Flavor Life Essential Oils. Please find your favorite scent. I scent my room with cedarwood before going to bed. It relaxes me and helps me fall asleep easily.
A Life with Aromatherapy [Flavor Life].

There are aroma diffusers that use special cartridges that use neither water nor oil. Unlike the typical ultrasonic vibration humidification system, it does not emit steam, making it comfortable to use even in the hot and humid summer months. Scents available are lavender, orange blossom, and jasmine.
Cartridge type aroma diffuser [EasyAroma]

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