The influence of bed firmness on sleep quality.

We studied the relationship between sleep quality and bed surface firmness. Nine men were investigated, sleeping in their homes for at least 5 consecutive nights on a soft and a more firm mattress using a sensor pad placed under the mattress and a solid-state recording device. The subjective feeling of sleep quality did not always agree with the recorded sleep data. The difference was most marked when changing from the subject's own to one of the test mattresses. For the same subject the results were reproducible between nights provided there were no external disturbing factors. Four of the 9 subjects slept significantly better on the softer of the two mattresses and 2 on the hard mattress. The difference in sleep quality observed among the subjects tested makes it necessary to relate the results to the same person rather than considering a whole group as an entity. The adaptation period for a new sleep surface extended to many days.

Descriptive physiological data on a sleep bruxism population.

We studied 24 bruxers (23-67 years old). They often complained of orofacial and bodily pain and presented autonomic symptoms (sweating 23%, palpitations at night 62%, decreased libido 50%); 19% had increased blood pressure requiring treatment, and 65% reported frequent headaches in the morning. Deep sleep and rapid eye movement (REM) were delayed. An average of 167 orofacial episodes developed during the night. The mean number of masseter bursts strictly defined as bruxism was 79, the mean delay for the first occurrence after sleep onset 18 minutes. The majority of bruxism occurred in stage 2 sleep and REM sleep. The mean number of shifts of sleep stages was 70, one-third occurring within the first minute following a bruxing episode, and 15% of bruxing episodes developed after a shift in sleep stage. Electroencephalogram showed alpha-delta pattern in 15% of the subjects. Short-lasting alpha activity was often encountered during the 10 seconds preceding the development of a bruxing episode. Tachycardia developed at its onset, persisting for 10 seconds. We suggest that, as a minor alarm response to endogenous/exogenous stimuli, arousal develops and is often followed by motor activation, such as a burst of bruxing, with, as in any situation when motor activity suddenly increases, a secondary increase of heart activity.

Sleep-related breathing and movement disorders in healthy elderly and demented subjects.

Reported findings regarding sleep and sleep disorders in the elderly often conflict. Differences in results across studies may arise from selection of subjects, definitions and recording conditions. Our purpose was to test a method to study elderly, both healthy and demented, under the most natural conditions, without disturbing a fragile sleep. Using clinical parameters and a non-disturbing recording method, we evaluated sleep quality in patients with carefully diagnosed dementia and compared the results to a group of healthy subjects between 50 and 70 years of age. Healthy subjects awoke less and had more quiet sleep than patients, while in patients a tendency for delayed sleep latency and more active sleep was observed. Consistent with previous investigations, sleep-related respiratory disorders (SRRD) were more common in patients than in the matched control group, and periodic breathing appeared only among patients. SRRD, of both obstructive and central types, were only mild, with periodic breathing dominating only among patients. Most of the desaturations were less than 10%. We did not observe respiration of the Cheyne-Stokes type. Patients had more sleep-related movement disorders (SRMD), particularly with increase of twitches and long movements. Periodic movements were not significantly increased among the patients. The method, and the data obtained may be useful for practitioners dealing with sleep disorders in geriatric populations. In the elderly, interactivity between sleep, SRRD and SRMD may be bidirectional and as elderly and demented subjects might have a distorted homeostatic sleep response, SRRD and SRMD, even in a mild form, may cause sleep disruption and worsen dementia.

Neurophysiological findings in the Rett syndrome, I: EMG, conduction velocity, EEG and somatosensory-evoked potential studies.

Nine girls, aged 10 to 22 years, with confirmed Rett syndrome--eight as stage IV and one at stage III--were investigated neurophysiologically. EMG and neurography studies were performed, and somatosensory-evoked responses (SER) were recorded as well as EEG with topographic mapping. Even in advanced clinical stages, no major motor root involvement or demyelinating motor peripheral neuropathy was detected on EMG or neurography, but an axonopathy, possibly of secondary origin, was observed. EEG showed slowing and dominance of low frequency activity of subcortical origin, with or without epileptic discharges. SER findings suggested involvement of the spinal cord and the spinothalamic system. Neurophysiological investigations can be used by the clinician in the differential diagnosis of the Rett syndrome.

Neurophysiological findings in the Rett syndrome, II: Visual and auditory brainstem, middle and late evoked responses.

Nine girls with the Rett syndrome (RS) were investigated neurophysiologically using evoked potentials techniques. Visual- (VER) and auditory-evoked responses, including the early (ABR), middle (MLR) and late components (ACR), were recorded. There was evidence of variable, multilevel impairment of the nervous system. While ABR and MLR indicated lesions at the brainstem and midbrain levels, the late responses and VER pointed to an intra-cerebral/cortical defect. It is suggested that the perceptual mechanisms still functioned and some discrimination properties remained.