Noriko Fukuda

Effects of vitamin B12 on plasma melatonin rhythm in humans: increased light sensitivity phase-advances the circadian clock?

Vitamin B12 (methylcobalamine) was administered orally (3 mg/day) to 9 healthy subjects for 4 weeks. Nocturnal melatonin levels after exposure to bright light (ca. 2500 lx) were determined, as well as the levels of plasma melatonin over 24 h. The timing of sleep was also recorded. Vitamin B12 was given blind to the subjects and crossed over with placebo. We found that the 24-h melatlonin rhythm was significantly phase-advanced (1.1. h) in the vitamin B12 trial as compared with that in the placebo trial. In addition, the 24-h mean of plasma melatonin level was much lower in the vitamin B12 traial than with the placebo. Furthermore, the nocturnal melatonin levels during bright light exposure were significantly lower in the vitamin B12 trial than with the placebo. On the other hand, vitamin B12 did not affect the timing of sleep. These findings raise the possibility that vitamin B12 phase-advances the human circadian rhythm by increasing the light sensitivity of the circadian clock.

Gender difference of slow wave sleep in middle aged and elderly subjects

Sleep EEG of eight healthy males and eight females aged 54–72 years were recorded at their homes. The electroencephalograms were visually scored and analyzed by spectral analysis using the FFT method. There were no significant differences in sleep parameters except for a higher percentage of stage 3 + 4 in females. The spectral power of the delta band EEG was classified into two frequencies: 0.5–2 Hz and 2–4 Hz. The total amount of the delta band spectral power through the night was significantly larger in females. Periodic fluctuation of delta band power was observed in females along with non‐rapid eye movement–rapid eye movement cycles.

Seasonality in human sleep.

The timing of sleep and sleep EEG parameters in 10 healthy male subjects were investigated in four seasons under controlled conditions. The phase of nocturnal sleep was delayed about one and a half hours in winter as compared to that in summer. The duration of stage 4 sleep decreased and REM sleep increased significantly in winter compared with summer. The seasonality in the timing of sleep can be explained by photoperiodic time cues, but the changes in sleep EEG parameters are diffucult to explain in terms of photoperiod.

Effects of bright light at lunchtime on sleep of patients in a geriatric hospital I

The effects of lunchtime bright light exposure in patients of a geriatric hospital were investigated. Ten inpatients (six women and four men; mean age ± SD: 81.2 ± 8.8 years) with sleep disturbances were studied for 9 weeks. Nurses performed daily ratings for sleep–wakefulness disturbances. Approximately 8000 lx bright light exposure was performed for 3 weeks in the light therapy room. Before and after exposure, ocular function was evaluated. Clinical ratings of sleep‐wakefulness improved in eight patients. The score of difficulty in falling asleep and drowsiness in the morning declined during the light exposure. The score of drowsiness in the afternoon decreased during the post‐light exposure. Post‐exposure ocular disturbances were not found.

Effects of moderately bright light on subjective evaluations in healthy elderly women

Eight healthy elderly women aged 56–72 years (mean age: 67.4 years) participated in this study. They were exposed to moderately bright light (1000 lux) for 1 h in the morning every 6 days in their homes. Moderately bright light improved self evaluations for alertness, mood, motivation, happiness, refreshment, concentration and appetite after the second exposure to the light. Sleep maintenance, anxiety and integrated sleep feeling also improved after the fourth exposure to the light. The phase of rectal temperature rhythm did not change in a moderately bright light condition. These results suggest that bright light influences sleep quality and self evaluations without changing the biological rhythm phase.

Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans ☆

Eight young males were subjected to a single blind cross-over test to see the effects of vitamin B12 (methylcobalamin; VB12) on the phase-response of the circadian melatonin rhythm to a single bright light exposure. VB12 (0.5 mg/day) or vehicle was injected intravenously at 1230 h for 11 days, which was followed by oral administration (2 mg x 3/day) for 7 days. A serial blood sampling was performed under dim light condition (less than 200 lx) and plasma melatonin rhythm was determined before and after a single bright light exposure (2500 lx for 3 h) at 0700 h. The melatonin rhythm before the light exposure showed a smaller amplitude in the VB12 trial than in the placebo. The light exposure phase-advanced the melatonin rhythm significantly in the VB12 trail, but not in the placebo. These findings indicate that VB12 enhances the light-induced phase-shift in the human circadian rhythm.

Effects of Menstrual Cycle on Plasma Melatonin Level and Sleep Characteristics

It is well known that some clinical symptoms (e.g. psychotic symptoms and epileptic seizures) often aggravate around the time of menstruation. Moreover, the change of subjective sleep feeling throughout the menstrual cycle was reported. Therefore, the menstrual cycle is presumed to affect sleep characteristics and biological rhythm. We investigated a circadian pattern of plasma melatonin and body temperature, and sleep characteristics in the different phases of the menstrual cycle under controlled environmental conditions. In this paper, a part of the results is discussed.

Effects of morning bright light on sleep in healthy elderly women

Subjective sleep feeling and polysomnography were measured in 10 elderly women to investigate the effects of 8000 lux morning bright light (BL) exposure. The profile of sleep feeling in the BL condition was better than in the control condition. The proportion of awakening time in the first one‐third of night sleep decreased, and the amount of awakening time in the last one‐third increased in BL condition. Daytime napping reduced in BL condition. These findings suggested the effectiveness of exposure to bright light on the improvement of sleep quality and daytime vigilance of healthy elderly women.

Gender differences in the sleep of middle-aged individuals.

Abstract The study was designed to investigate gender differences in the sleep‐wake patterns of healthy middle‐aged individuals in their home environment. Polysomnography showed that daytime napping was more common in men than in women. Men had lower sleep efficiency index and experienced more stage 1 sleep. Males had significantly less stages 3 + 4 sleep, less stage REM sleep, and more transitions to wake from REM sleep. Men could not maintain stage REM as well as women. This study indicates that the gender differences in the sleep‐wake patterns have appeared in a group of middle‐aged individuals.

Motor activity rhythm in dementia with delirium

Abstract Using an actigraph, the activity patterns in 13 demented patients with delirium were examined. We analyzed the data of the eight patients, wearing the actigraphs for more than 10 days. They were classified into four types:type A, nocturnal delirium type; type B, wandering type; type C, hypobulia type; and type D, lying down type. The day to day activity variation was most prominent in type A and seemingly the least in type B. The dominant period of activity rhythm was nearly 24 h in all cases. Additional 12‐h period was observed in type C. Actigraphs might become useful in making therapeutic decisions regarding demented patients with delirium.