IEEE Transactions on Biomedical Engineering, Feb 1, 2014
Wrist actigraphy (ACT) is a low-cost and well-established technique for long-term monitoring of h... more Wrist actigraphy (ACT) is a low-cost and well-established technique for long-term monitoring of human activity. It has a special relevance in sleep studies, where its noninvasive nature makes it a valuable tool for behavioral characterization and for the detection and diagnosis of some sleep disorders. The traditional sleep/wakefulness state estimation algorithms from the nocturnal ACT data are unbalanced from a sensitivity and specificity points of view since they tend to overestimate sleep state, with severe consequences from a diagnosis point of view. They usually maximize the overall accuracy that does not take into account the highly unbalanced state distribution. In this paper, a method is proposed to appropriately deal with this unbalanced problem, achieving similar sensitivity and specificity scores in the state estimation process. The proposed method combines two linear discriminant classifiers, trained with two different criteria involving movement detection to generate a first state estimate. This result is then refined by a Hidden Markov Model-based algorithm. The global accuracy, the sensitivity, and the specificity of the method are 77.8%, 75.6%, and 81.6%, respectively, performing better than the tested algorithms. If the performance is assessed only for movement periods, this improvement is even higher.
In this paper a definition of the activity (ACT) variable is proposed and a method to estimate it... more In this paper a definition of the activity (ACT) variable is proposed and a method to estimate it from the noisy actigraph output sensor data is described. A statistical model for the actigraph data generation process is suggested based on its working physical principles and on physiological considerations about human activity. The purposeless nature of the sleeping movements is used
International Journal of Psychiatry in Clinical Practice, 1997
Clinical and sleep EEG effects of trazodone in major depression were investigated using a 5-week ... more Clinical and sleep EEG effects of trazodone in major depression were investigated using a 5-week single-blind study design. Nine patients with DSM-N major depression were selected. Trazodone (50-250 mg) was given following a 2-week placebo run-in period. Both sleep and psychiatric evaluations were performed at different time points. Early and persistent sleep-inducing effects were detected, including the improvement of objective insomnia features and increased amounts of slow wave sleep. However, no significant changes of REM sleep measures were found. The sleep EEG changes seem to be related to the clinical improvement of both anxiety and insomnia, but there is no apparent relationship with the antidepressant action, which occurs at a later stage of the treatment. Trazodone may be useful in depressed patients, either as a hypnotic-like agent or as an effective antidepressant drug with beneficial effects on sleep.
Epidemiologic analysis of sleep disorders (SDs) in children and adolescents faces several difficu... more Epidemiologic analysis of sleep disorders (SDs) in children and adolescents faces several difficulties. There is a marked interindividual variability during the first years of life, which is more relevant in the first 2 years, and consequently the definition of what is “normal” can become a difficult issue to which cultural and ethnic differences might add clear complexity. Furthermore many available survey lack objective data; this issue is particularly relevant whenever data are provided by the caregivers, since known discrepancies do exist between children and caregivers information, and the fact that data obtained from younger individual are subjected to important ethical regulations is likely to reduce the number of available studies. Other contributing issues are the position of pediatric sleep in the field of sleep medicine and the successive classifications of sleep disorders and the methodologic modifications, rendering difficult comparisons across decades.
A neurology teleconsulting network was implemented between a university hospital in Lisbon and fi... more A neurology teleconsulting network was implemented between a university hospital in Lisbon and five nearby health centres. PCs equipped for videoconferencing were installed, connected by ISDN lines at 128 kbit/s. Fifty-three general practitioners (GPs) were surveyed. The survey showed that the GPs had difficulties in using computers, but they had definite intentions to use teleconsultation for neurology cases and 83% of the respondents stated that they would probably use the technique. During the study, 90 neurology teleconsultations took place over 55 weeks. The average consultation rate was 1.6 teleconsultations per week (SD 1.3, range 0-6). The conferences lasted 10-45 min. Longer teleconsultations were mainly due to technical difficulties in using computers on the part of users with a low level of computer literacy. The patients were 42 males and 46 females, with a mean age of 38 years (SD 20, range 1-84); two patients were discussed twice. The benefits consisted mainly of advice on patient medication, diagnosis and the prevention of unnecessary specialist consultations or laboratory examinations. Doctor-doctor teleconsultation allows the rapid resolution of queries which otherwise cause stress to patients and increase the cost and complexity of care.
World Journal of Biological Psychiatry, Jan 15, 2013
The aim of this study was to examine the differences between a sample of patients with schizophre... more The aim of this study was to examine the differences between a sample of patients with schizophrenia and a sample of healthy controls in terms of sleep patterns and self-reported sleep quality and quality of life (QoL). Thirty-four schizophrenia outpatients (SP), 12 women and 22 men and 34 healthy subjects (HS), 15 women and 19 men, participated in this study. Wrist-actigraphy recordings and a sleep diary were used for sleep-wake cycle assessment. The quality of sleep was measured using the Pittsburgh Sleep Quality Index (PSQI), the QoL was evaluated using the World Health Organization Quality of Life - Abbreviated version (WHOQOL-Bref). The Positive and Negative Syndrome Scale (PANSS) was used for psychopathology assessment. Patients sleep more at night, but have poorer sleep efficiency, than HS. Sleep latency and nighttime awakenings were significantly higher in SP. Self-reported QoL scores were significantly higher, in all four domains, in HS. Scores on PSQI were significantly higher in SP, indicating a worse quality of sleep. Two disturbed patterns of sleep-wake phase were found in SP: advance sleep-phase syndrome (ASPS) (N = 3) and irregular sleep-wake rhythm (N = 3). Schizophrenia patients have more disturbed sleep-wake patterns and poor sleep quality and quality of life compared with healthy controls.
IEEE Transactions on Biomedical Engineering, Feb 1, 2014
Wrist actigraphy (ACT) is a low-cost and well-established technique for long-term monitoring of h... more Wrist actigraphy (ACT) is a low-cost and well-established technique for long-term monitoring of human activity. It has a special relevance in sleep studies, where its noninvasive nature makes it a valuable tool for behavioral characterization and for the detection and diagnosis of some sleep disorders. The traditional sleep/wakefulness state estimation algorithms from the nocturnal ACT data are unbalanced from a sensitivity and specificity points of view since they tend to overestimate sleep state, with severe consequences from a diagnosis point of view. They usually maximize the overall accuracy that does not take into account the highly unbalanced state distribution. In this paper, a method is proposed to appropriately deal with this unbalanced problem, achieving similar sensitivity and specificity scores in the state estimation process. The proposed method combines two linear discriminant classifiers, trained with two different criteria involving movement detection to generate a first state estimate. This result is then refined by a Hidden Markov Model-based algorithm. The global accuracy, the sensitivity, and the specificity of the method are 77.8%, 75.6%, and 81.6%, respectively, performing better than the tested algorithms. If the performance is assessed only for movement periods, this improvement is even higher.
In this paper a definition of the activity (ACT) variable is proposed and a method to estimate it... more In this paper a definition of the activity (ACT) variable is proposed and a method to estimate it from the noisy actigraph output sensor data is described. A statistical model for the actigraph data generation process is suggested based on its working physical principles and on physiological considerations about human activity. The purposeless nature of the sleeping movements is used
International Journal of Psychiatry in Clinical Practice, 1997
Clinical and sleep EEG effects of trazodone in major depression were investigated using a 5-week ... more Clinical and sleep EEG effects of trazodone in major depression were investigated using a 5-week single-blind study design. Nine patients with DSM-N major depression were selected. Trazodone (50-250 mg) was given following a 2-week placebo run-in period. Both sleep and psychiatric evaluations were performed at different time points. Early and persistent sleep-inducing effects were detected, including the improvement of objective insomnia features and increased amounts of slow wave sleep. However, no significant changes of REM sleep measures were found. The sleep EEG changes seem to be related to the clinical improvement of both anxiety and insomnia, but there is no apparent relationship with the antidepressant action, which occurs at a later stage of the treatment. Trazodone may be useful in depressed patients, either as a hypnotic-like agent or as an effective antidepressant drug with beneficial effects on sleep.
Epidemiologic analysis of sleep disorders (SDs) in children and adolescents faces several difficu... more Epidemiologic analysis of sleep disorders (SDs) in children and adolescents faces several difficulties. There is a marked interindividual variability during the first years of life, which is more relevant in the first 2 years, and consequently the definition of what is “normal” can become a difficult issue to which cultural and ethnic differences might add clear complexity. Furthermore many available survey lack objective data; this issue is particularly relevant whenever data are provided by the caregivers, since known discrepancies do exist between children and caregivers information, and the fact that data obtained from younger individual are subjected to important ethical regulations is likely to reduce the number of available studies. Other contributing issues are the position of pediatric sleep in the field of sleep medicine and the successive classifications of sleep disorders and the methodologic modifications, rendering difficult comparisons across decades.
A neurology teleconsulting network was implemented between a university hospital in Lisbon and fi... more A neurology teleconsulting network was implemented between a university hospital in Lisbon and five nearby health centres. PCs equipped for videoconferencing were installed, connected by ISDN lines at 128 kbit/s. Fifty-three general practitioners (GPs) were surveyed. The survey showed that the GPs had difficulties in using computers, but they had definite intentions to use teleconsultation for neurology cases and 83% of the respondents stated that they would probably use the technique. During the study, 90 neurology teleconsultations took place over 55 weeks. The average consultation rate was 1.6 teleconsultations per week (SD 1.3, range 0-6). The conferences lasted 10-45 min. Longer teleconsultations were mainly due to technical difficulties in using computers on the part of users with a low level of computer literacy. The patients were 42 males and 46 females, with a mean age of 38 years (SD 20, range 1-84); two patients were discussed twice. The benefits consisted mainly of advice on patient medication, diagnosis and the prevention of unnecessary specialist consultations or laboratory examinations. Doctor-doctor teleconsultation allows the rapid resolution of queries which otherwise cause stress to patients and increase the cost and complexity of care.
World Journal of Biological Psychiatry, Jan 15, 2013
The aim of this study was to examine the differences between a sample of patients with schizophre... more The aim of this study was to examine the differences between a sample of patients with schizophrenia and a sample of healthy controls in terms of sleep patterns and self-reported sleep quality and quality of life (QoL). Thirty-four schizophrenia outpatients (SP), 12 women and 22 men and 34 healthy subjects (HS), 15 women and 19 men, participated in this study. Wrist-actigraphy recordings and a sleep diary were used for sleep-wake cycle assessment. The quality of sleep was measured using the Pittsburgh Sleep Quality Index (PSQI), the QoL was evaluated using the World Health Organization Quality of Life - Abbreviated version (WHOQOL-Bref). The Positive and Negative Syndrome Scale (PANSS) was used for psychopathology assessment. Patients sleep more at night, but have poorer sleep efficiency, than HS. Sleep latency and nighttime awakenings were significantly higher in SP. Self-reported QoL scores were significantly higher, in all four domains, in HS. Scores on PSQI were significantly higher in SP, indicating a worse quality of sleep. Two disturbed patterns of sleep-wake phase were found in SP: advance sleep-phase syndrome (ASPS) (N = 3) and irregular sleep-wake rhythm (N = 3). Schizophrenia patients have more disturbed sleep-wake patterns and poor sleep quality and quality of life compared with healthy controls.
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