nervous system,its main component,linalool,is used as a compound to study its effects compared with plain lavender oil.It is noteworthy that Heuberger et al2)found the reduction of blood pressure and ■Left anterior skin temperature after applying linalool to the skin of Right anterior Left posterior participants.In addition,linalool has a lot of isoforms ■Right posterior in nature such as R)(),(S)-(+)-and (RS)-(+)-forms One study using R-(-)-linalool found similar effects from this compound on the autonomic nervous system parameters and also promoted calming and Base oil feelings of vigor2).According to the pharmacokinetic Fig.1 The power ofalpha activity showed no significantly properties of linalool,Yamada4 was able to show the different between left and right side of the brain lipophilic properties of the linalool was suitable for transporting this compound across the blood-brain barrier.When reaching the brain,linalool can bind with the GABA(gamma aminobutyric acid)receptors similar to the benzodiazepines and caused relaxing and sedative effects.In one study,they found linalool could potentiate the effects of GABA,the main inhibitor neurotransmitters of the human brain in the amygdala,the subcortical brain area involved in the Eye close Sweet almond oil inhalation Lavender inhalation emotional response to the environment25).The effect of linalool on the amygdala may explain the mood Fig.2 Brain Topographical map of the distribution of effects oflavender. alpha brainwave activity.The red areas indicate a It is felt the effects of lavender inhalation on significantly increase of power in bilateral temporal and central area during inhalation of lavender the brain wave activities are well demonstrated in the present study.During inhalation with lavender,the power of theta(4-8 Hz)and alpha (8-13 Hz)activities heart rate,respiratory rate and skin temperature)were are significantly increased in all brain regions.This recorded as indicators of the arousal level of the result is consistent with the study of Diego()that nervous system.In addition,subjects had to rate their found after lavender inhalation that frontal alpha mood state in terms of good,bad,active,drowsy,fresh, power was significantly increased.Furthermore. relaxed.stressed.uncomfortable.romantic.frustrated. a study conducted at the University of Occupational calm,and disgusted in order to assess subjective and Environmental Health,Kitakyushu Japan26)used behavioral arousal. changes of electroencephalogram (EEG)to measure Inhalation of lavender oil significantly the effects of aromas.The present study found decreased the level of ANS arousal,namely.decreases relaxing effects with increases of alpha wave activities of blood pressure,heart rate,and skin temperature. after administering lavender,cineol sandalwood,and These changes of the ANS parameters represent the alpha-pinene.The EEG evidence of relaxation can be function of parasympathetic nervous system that seen in various practices such as meditation counteracts the function of sympathetic nervous Meditation is a way of balancing the body and the system.As for mood states,subjects felt better,fresher, mind as well as controlling the mind to experience more active,more relaxed,and less drowsy.This finding feelings of peace and relaxation.The study among points towards a decrease of arousal as assessed people meditating can demonstrate similar EEG through subjective self-evaluation.The results of the changes with lavender inhalation,which presented as present study support previous studies indicating an increase in theta and alpha activities in the brain lavender odor can influence relaxing during meditation27.The increase in theta and alpha Previous studies using a footbath containing activities can also be observed even during pre- lavender oil also supports the positive effects on the meditation states in people who frequently practice parasympathetic neural activity of lavender oile.To meditation2.These results lend support that increases study the underlying mechanism of lavender oil on the in theta and alpha wave activity causes a range of J MedAssoc Thai VoL 95 No.4 2012 603J Med Assoc Thai Vol. 95 No. 4 2012 603 heart rate, respiratory rate and skin temperature) were recorded as indicators of the arousal level of the nervous system. In addition, subjects had to rate their mood state in terms of good, bad, active, drowsy, fresh, relaxed, stressed, uncomfortable, romantic, frustrated, calm, and disgusted in order to assess subjective behavioral arousal. Inhalation of lavender oil significantly decreased the level of ANS arousal, namely, decreases of blood pressure, heart rate, and skin temperature. These changes of the ANS parameters represent the function of parasympathetic nervous system that counteracts the function of sympathetic nervous system. As for mood states, subjects felt better, fresher, more active, more relaxed, and less drowsy. This finding points towards a decrease of arousal as assessed through subjective self-evaluation. The results of the present study support previous studies indicating lavender odor can influence relaxing Previous studies using a footbath containing lavender oil also supports the positive effects on the parasympathetic neural activity of lavender oil(21). To study the underlying mechanism of lavender oil on the nervous system, its main component, linalool, is used as a compound to study its effects compared with plain lavender oil. It is noteworthy that Heuberger et al(22) found the reduction of blood pressure and skin temperature after applying linalool to the skin of participants. In addition, linalool has a lot of isoforms in nature such as R)-(−)-, (S)-(+)- and (RS)-(+)- forms. One study using R-(−)-linalool found similar effects from this compound on the autonomic nervous system parameters and also promoted calming and feelings of vigor(23). According to the pharmacokinetic properties of linalool, Yamada(24) was able to show the lipophilic properties of the linalool was suitable for transporting this compound across the blood-brain barrier. When reaching the brain, linalool can bind with the GABA (gamma aminobutyric acid) receptors similar to the benzodiazepines and caused relaxing and sedative effects. In one study, they found linalool could potentiate the effects of GABA, the main inhibitor neurotransmitters of the human brain in the amygdala, the subcortical brain area involved in the emotional response to the environment(25). The effect of linalool on the amygdala may explain the mood effects of lavender. It is felt the effects of lavender inhalation on the brain wave activities are well demonstrated in the present study. During inhalation with lavender, the power of theta (4-8 Hz) and alpha (8-13 Hz) activities are significantly increased in all brain regions. This result is consistent with the study of Diego(8) that found after lavender inhalation that frontal alpha power was significantly increased. Furthermore, a study conducted at the University of Occupational and Environmental Health, Kitakyushu Japan(26) used changes of electroencephalogram (EEG) to measure the effects of aromas. The present study found relaxing effects with increases of alpha wave activities after administering lavender, cineol sandalwood, and alpha-pinene. The EEG evidence of relaxation can be seen in various practices such as meditation. Meditation is a way of balancing the body and the mind as well as controlling the mind to experience feelings of peace and relaxation. The study among people meditating can demonstrate similar EEG changes with lavender inhalation, which presented as an increase in theta and alpha activities in the brain during meditation(27). The increase in theta and alpha activities can also be observed even during pre￾meditation states in people who frequently practice meditation(28). These results lend support that increases in theta and alpha wave activity causes a range of Fig. 2 Brain Topographical map of the distribution of alpha brainwave activity. The red areas indicate a significantly increase of power in bilateral temporal and central area during inhalation of lavender Fig. 1 The power of alpha activity showed no significantly different between left and right side of the brain