Impact of Temporal Lobe Epilepsy on Phonological Processing and Reading: A Case Study of Identical Twins

In order to evaluate the possible consequences of temporal lobe epilepsy on reading acquisition, we first compared the reading skills and phonological awareness abilities in a set of 13-year-old identical twins, one of whom is affected by temporal lobe epilepsy (LB). We then compared their performances to those of an age- and IQ-matched control group. Both siblings have an intellectual quotient above average as well as normal memory and linguistic abilities. Results showed that the reading age of LB (assessed by the Lefabvrais French reading test) was more than two years behind expectations whereas that of her sister was above average. Further, in contrast to her sister and healthy control subjects, LB exhibited specific deficits in elaborate metaphonological awareness abilities (non-word repetition, rhyme production, phonemic segmentation and syllabic inversion). These could be linked to temporal lobe dysfunction, thus confirming the important role of the temporal lobes in reading acquisition.     

24-h activity rhythm and sleep in depressed outpatients

Disturbances in sleep and circadian rest-activity rhythms are key features of depression. Actigraphy, a non-invasive method for monitoring motor activity, can be used to objectively assess circadian rest-activity rhythms and sleep patterns. While recent studies have measured sleep and daytime activity of depressed patients using wrist-worn actigraphy, the actigraphic 24-h rest-activity rhythm in depression has not been well documented. We aimed to examine actigraphically measured sleep and circadian rest-activity rhythms in depressed outpatients. Twenty patients with DSM-IV major depressive episode and 20 age- and sex-matched healthy controls participated in this study. Participants completed 7 consecutive days of all-day actigraphic activity monitoring while engaging in usual activities. For sleep parameters, total sleep time, wake after sleep onset, and sleep fragmentation index were determined. Circadian rhythms were estimated by fitting individual actigraphy data to a cosine curve of a 24-h activity rhythm using the cosinor method, which generated three circadian activity rhythm parameters, i.e., MESOR (rhythm-adjusted mean), amplitude, and acrophase. Subjective sleep was also assessed using a sleep diary and the Pittsburgh Sleep Quality Index. Patients showed significantly lower MESOR and more dampened amplitude along with significant sleep disturbances. Logistic regression analysis revealed that lower MESOR and more fragmented sleep emerged as the significant predictors of depression. Correlations between subjectively and actigraphically measured parameters demonstrated the validity of actigraphic measurements. These results indicate marked disturbances in sleep and circadian rest-activity rhythms of depression. By simultaneously measuring sleep and rest-activity rhythm parameters, actigraphy might serve as an objective diagnostic aid for depression.     

Sleep disturbances and cognitive impairment in schizophrenia spectrum disorders: a systematic review and narrative synthesis

Individuals with schizophrenia spectrum disorders (SSD) experience frequent sleep disturbances in addition to enduring cognitive impairments. The purpose of the present review was to systematically summarise our current understanding of the association between sleep disturbances and cognition in SSD. Through this, it was aimed to identify features of disturbed sleep that are reliably associated with cognitive deficits in SSD and identify the gaps within the current literature that require future investigation. Eighteen relevant studies were identified following a two-stage screening process. Following a structured narrative synthesis of key study components, no clear and consistent pattern emerged. Considerable methodological variability was present amongst the reviewed studies. Although some broad consistencies were identified, such as associations between sleep spindle density and sleep-dependent memory consolidation, the overall pattern of results lacked a cohesive composition due to the diverse list of sleep parameters and cognitive domains investigated, as well as a lack of replication. Additional research is needed before more definitive remarks can be made regarding the influence of sleep disturbances on cognitive function in SSD.     

Individuals with pain need more sleep in the early stage of mild traumatic brain injury

ObjectiveHypersomnia is frequently reported after mild traumatic brain injury (mTBI), but its cause(s) remain elusive. This study examined sleep/wake activity after mTBI and its association with pain, a comorbidity often associated with insomnia.MethodsActigraphy recording was performed for 7 ± 2 consecutive days in 56 individuals at one month post-mTBI (64% male; 38 ± 12 years), 24 individuals at one year post-mTBI (58% male; 44 ± 11years), and in 20 controls (50% male; 37 ± 12 years). Pain intensity and its effect on quality of life was assessed with a visual analogue scale and the Short Form Health Survey (SF-36) bodily pain subscale.ResultsOverall, few differences in sleep/wake patterns were found between mTBI patients and controls. However, higher percentages of mTBI individuals with moderate-to-severe pain were found to require more than eight hours of sleep per day (37% vs11%; p = 0.04) and to be frequent nappers (defined as those who took three or more naps per week) (42% vs 22%; p = 0.04) compared to those with mild or no pain at one month postinjury. Correcting for age and depression, The SF-36 score was found to be a significant predictor of sleep duration exceeding eight hours per day at one month (odds ratio = 0.95; 95% confidence interval = 0.92–0.99; p = 0.01), but not at one year post-mTBI. Pain and increased sleep need (in terms of hours per day or napping frequency) were found to co-exist in as much as 29% of mTBI patients at one month postinjury.ConclusionPain could be associated with more pronounced sleep need in about one-third of mTBI patients during early recovery. Unalleviated pain, found in more than 60% of mTBI patients, should therefore be looked for in all mTBI patients reporting new onset of sleep disorder, not only in those with insomnia.     

The influence of intensity and timing of daily light exposure on subjective and objective sleep in adolescents with an evening circadian preference

Study objectivesThe aim of the present study is to examine the relationship between light and sleep, in adolescents with an evening circadian preference.MethodsFor a period of seven days, ninety-nine adolescents wore a wrist actigraph to assess light exposure and objective sleep and completed a sleep diary to assess subjective sleep.ResultsLower average light intensity across the preceding 24 h was associated with a later sleep onset (p < 0.01) and a later next-day sleep offset (p < 0.05). A later time of last exposure to more than 10 lux was associated with a later sleep onset (p < 0.001) and a shorter objective total sleep time (p < 0.001), as well as a later bedtime (p < 0.001) and a shorter subjective total sleep time (p < 0.001). Furthermore, exploratory analyses found that lower average early morning light exposure (between 4 and 9 AM) was associated with later sleep onset (p < 0.05), a later next-day sleep offset (p < 0.05), and a later next-day waketime (p < 0.01), lower average afternoon light exposure (between 2 and 7 PM) was associated with a later next-day sleep offset (p < 0.05), and lower average evening light exposure (between 7 PM and 12 AM) was associated with longer subjective total sleep time (p < 0.01).ConclusionThis study highlights the importance of light exposure, particularly the timing of light exposure, for establishing healthy patterns of sleep among adolescents with a propensity for a delayed bedtime and waketime. These findings provide additional evidence for targeting light exposure when designing interventions to improve adolescent sleep.     

Racial disparities in sleep health between Black and White young adults: The role of neighborhood safety in childhood

ObjectivesBlack adults in the United States have shorter sleep durations and poorer sleep efficiency relative to White adults, yet reasons for these disparities are not well explicated. The objective of this study was to examine neighborhood safety in childhood as a mediator of subsequent racial disparities in sleep.MethodsData were from Black and White young adults attending a large, predominantly White university in the Southeastern United States (N = 263; 52% Black, 53% female; Mean age = 19.21 years, SD = 1.01). Sleep parameters were assessed from eight nights of wrist actigraphy (time in bed, sleep duration, and efficiency) and an established self-report measure of daytime sleepiness. Residential histories from birth through age 18 were documented, and retrospective self-reports of neighborhood safety in childhood were assessed.ResultsBlack participants had less time in bed (p < 0.001), shorter sleep duration (p < 0.001), poorer sleep efficiency (p < 0.001), and more daytime sleepiness (p = 0.009) than White participants. Neighborhood safety mediated race differences in time in bed (p = 0.028), sleep duration (p = 0.033), and daytime sleepiness (p = 0.048), but not sleep efficiency. Findings were substantively unchanged after adjustment for family socioeconomic status, BMI, and substance use.ConclusionsFindings support the hypothesis that neighborhood safety in childhood may partially account for race differences in subsequent sleep duration and daytime sleepiness. Addressing racial inequities in childhood neighborhood safety may be an important step toward reducing racial disparities in sleep health.