Sleep disturbance-related depressive symptom and brain volume reduction in shift-working nurses.

Disturbed sleep is the most common effect of shift work. A large corpus of research indicates an association between sleep disturbance and depressive symptom in shift workers. In this study, we proposed the mediating role of grey matter (GM) structure in the relationship between sleep disturbance and depressive symptom. We collected structural MRI (sMRI) data as well as assessing the level of sleep disturbance and depressive symptom with the Pittsburgh Sleep disturbance Index and Zung Self-Rating Depression Scale, respectively, in 20 shift-working nurses and 19 day-working nurses. The shift-working nurses reported greater severity of sleep disturbance and depressive symptom, and furthermore, they exhibited reduced GM volume in the left postcentral gyrus (PostCG), right PostCG, right paracentral lobule, and left superior temporal gyrus (STG), compared to the day-working nurses. For each of the four brain regions, we formulated a mediation hypothesis by developing a mediation model that represents a causal chain between GM volume, sleep disturbance, and depressive symptom. Tests of the hypothesis on the mediation of GM volume revealed that inter-individual variations in left PostCG volume and left STG volume accounted for the influence of sleep disturbance on depressive symptom. These results suggest that structural alterations in PostCG and STG play an intervening role in the development of depressive symptom following sleep disturbance. We propose the need of considering neuroanatomical abnormalities in explaining and understanding symptomatic changes induced by sleep disturbance.

Amplitude-integrated EEG in infants with neonatal abstinence syndrome.

BACKGROUND: To describe amplitude-integrated encephalogram (aEEG) characteristics of neonates with neonatal abstinence syndrome (NAS). METHODS: This is a prospective observational study. Newborns exposed to prenatal opioids and their gestational matched controls were included. A single-channel aEEG was obtained using Olympic 6000 CFM monitor. The background activity (continuous/discontinuous), the amplitudes (µV) and the presence of sleep-wake cycle (SWC) were documented. RESULTS: A total of 59 infants, 23 with NAS and 36 controls were enrolled. All aEEG were completed within 48 hours of life prior to initiation of treatment. Birth weight and gestational age were similar in both groups. An aEEG was abnormal (discontinuous pattern and/or absent SWC) in 78 % (18/23) of infants with NAS versus only 25% in control group (9/36), [OR 10.8, CI (2.7-46.5) P < 0.001]. 61% of infants with NAS had discontinuous pattern [OR 7.8, CI (2-32) P = 0.001] and 39% had absence of sleep-wake cycle [OR 7.1, CI (1.4-39.4) P = 0.007]. CONCLUSIONS: A majority of infants with NAS have abnormal aEEG activity.

Functional connectivity of the circadian clock and neural substrates of sleep-wake disturbance in delirium.

A possible mechanism of disrupted circadian rhythms in delirium was identified using resting-state functional connectivity. Thirty-four delirious patients and 38 non-delirious controls were scanned for resting-state functional MRI. Seed-based connectivity of the suprachiasmatic nucleus was compared between the groups. In delirious patients functional connectivity from the circadian clock was increased to the dorsal anterior cingulate cortex and decreased to the posterior cingulate cortex, parahippocampal gyrus, cerebellum, and thalamus. A dysregulation of the default mode network and mental coordination processing areas by the circadian clock may be the underlying pathophysiology of sleep-wake cycle disturbance and symptom fluctuation in delirium.

Sleep-wake pattern following gunshot suprachiasmatic damage.

BACKGROUND: The suprachiasmatic nucleus (SCN) plays a critical role in maintaining melatonin and sleep-wake cycles. METHODS/PATIENT: We report a case of 38-year-old woman who, after gunshot wound to the right temple, developed a sleep complaint of multiple nocturnal awakenings and several naps throughout the day. RESULTS: Computerized tomography and magnetic resonance imaging revealed bilateral optic nerve and optic chiasm damage. Diagnostic polysomnography and actigraphy revealed an irregular sleep wake rhythm. CONCLUSIONS: We speculate concurrent damage of the SCN and optic nerves bilaterally resulted in the posttraumatic irregular sleep-wake rhythm.