Yuriko Ogawa

Effect of bright light exposure on muscle sympathetic nerve activity in human.

To evaluate the effect of bright light on the sympathetic nervous system in human, muscle sympathetic nerve activity (MSNA) was recorded from the peroneal nerve in five healthy subjects. Each subject was exposed to bright light of 5000 lx for 20 min. After the bright light exposure, MSNA became significantly enhanced. The heart rate increased transiently only during the bright light exposure. The blood pressure did not change significantly during and after the bright light exposure. The result is the first direct evidence showing that bright light modulates the activity of the sympathetic nervous system in normal human.

Effects of Yoku-kan-san-ka-chimpi-hange on the sleep of normal healthy adult subjects

Abstract Yoku‐kan‐san‐ka‐chimpi‐hange (YKCH) is a drug used for insomnia in Japanese traditional herbal medicine. The present study evaluated the effects of YKCH on sleep by all‐night polysomnography using the double‐blind method. Yoku‐kan‐san‐ka‐chimpi‐hange increased the total sleep time significantly, and tended to cause an increase in sleep efficiency and of stage 2 sleep, as well as a decrease of sleep latency and of stage 3 + 4 sleep. There was no apparent influence on rapid eye movement (REM) sleep. In terms of non‐REM sleep, the effects of YKCH exhibit a profile similar to those of benzodiazepines.

Diazepam reduces both arterial blood pressure and muscle sympathetic nerve activity in human.

It is known that benzodiazepines have a hypotensive effect, but the mechanism has not been well elucidated yet. To clarify whether this effect is due to central or peripheral mechanism, we administered 5 mg of diazepam or saline intravenously to healthy volunteers and assessed the change in blood pressure, heart rate, muscle sympathetic nerve activity and heart rate variability. After diazepam administration, systolic and mean blood pressure decreased significantly. Muscle sympathetic nerve activity was also significantly reduced but heart rate did not change, whereas the variables of spectral analysis of heart rate variability did not show significant change. We concluded that the hypotensive effect of diazepam in human is mainly due to the central mechanism.

The effects of oral melatonin on the autonomic function in healthy subjects.

We investigated the influence of melatonin on the human autonomic functions by measuring muscle sympathetic nerve activity (MSNA). Five healthy male volunteers took 3 mg of melatonin, and their plasma melatonin concentration, blood pressure, heart rate, and burst rate of MSNA were then recorded. The peak level of melatonin concentration showed a marked interindividual variation. Blood pressure was reduced significantly, while heart rate and burst rate of MSNA did not change significantly. These results indicate that melatonin has a hypotensive effect on blood pressure, and the central cardiovascular regulatory mechanism such as lowering of the baroreflex setpoint would be involved in the effect.

Hypocretin-1 (orexin-A) concentrations in cerebrospinal fluid are low in patients with Guillain-Barré syndrome

Abstract It is reported that cerebrospinal fluid (CSF) hypocretin‐1 (orexin‐A) concentrations in patients with narcolepsy are significantly low. Human narcolepsy is also known to be closely associated with a specific human histocompatibility leukocyte antigen (HLA), suggesting that autoimmunity is involved in the pathophysiology of the disease. Thus, it is important to know whether hypocretin changes are found in definite neuroimmunological diseases such as multiple sclerosis and Guillain–Barré syndrome (GBS). The results of the present study indicate that some patients with GBS have lower levels of CSF hypocretin‐1.

CSF hypocretin measures in patients with obstructive sleep apnea.

The majority of patients with narcolepsy‐cataplexy were reported to have very low cerebrospinal fluid (CSF) hypocretin‐1 (orexin‐A) levels. The hypocretin‐1 levels of secondary excessive daytime sleepiness (EDS) disorders are not known. In this study, we found that CSF hypocretin levels in the patients with obstructive sleep apnea syndrome were within the control range. The low hypocretin levels seem to reflect only the presence of cataplexy and DR2 positive in narcoleptics but not EDS itself.

Effects of donepezil (Aricept) on the rapid eye movement sleep of normal subjects

Abstract Donepezil (Aricept) is a therapeutic drug for the treatment of Alzheimer’s disease (AD). However, there have been only two reports describing the effects of donepezil on sleep as assessed by nocturnal polysomnography (PSG). With this in mind, the effects of donepezil on the sleep of healthy subjects was evaluated using PSG. The results indicated that the percentage of rapid eye movement sleep to total sleep time was increased significantly by a single dose of 5 mg of donepezil when given to healthy subjects immediately before retiring to bed.

Hypersomnia due to acute disseminated encephalomyelitis in a 5-year-old girl

A 5-year-old girl suffering from hypersomnia due to acute disseminated encephalomyelitis (ADEM) is reported. Brain CT revealed a large low-density lesion involving the lentiform nucleus, posterior limb of the internal capsule, thalamus, posterior hypothalamus and midbrain in the left side. She was treated with intravenous dexamethazone. After the initial dose of dexamethazone, hypersomnia was dramatically and rapidly improved. A later brain CT study disclosed that the lesion in the brain disappeared. The brain lesion in this case involved the waking center in the brain, which was described by Von Economo. We concluded that hypersomnia in this case was due to ADEM involving the neural mechanism for maintaing wakefulness, probably in the thalamus and posterior hypothalamus. Repeat all night polysomnograpy in this case disclosed prolonged total sleep time and increased amount of stage 3-4 sleep in the hypersomniac state.

Sleep-disordered breathing in a patient with congenital myopathy

Abstract A case of adult onset myopathy who showed a peculiar sleep‐related respiratory disorder (SRRD) is reported. She recovered from respiratory failure after tracheostomy and/or with the aid of the respirator used only during the night. Sleep study without the use of respirator revealed that her sleep was highly fragmented by frequent arousal responses due to inspiratory effort but not by apnea or hypopnea. To our knowledge this type of SRRD has not been described.