Sushanth Bhat

Is There a Clinical Role For Smartphone Sleep Apps? Comparison of Sleep Cycle Detection by a Smartphone Application to Polysomnography

STUDY OBJECTIVES Several inexpensive, readily available smartphone apps that claim to monitor sleep are popular among patients. However, their accuracy is unknown, which limits their widespread clinical use. We therefore conducted this study to evaluate the validity of parameters reported by one such app, the Sleep Time app (Azumio, Inc., Palo Alto, CA, USA) for iPhones. METHODS Twenty volunteers with no previously diagnosed sleep disorders underwent in-laboratory polysomnography (PSG) while simultaneously using the app. Parameters reported by the app were then compared to those obtained by PSG. In addition, an epoch-by-epoch analysis was performed by dividing the PSG and app graph into 15-min epochs. RESULTS There was no correlation between PSG and app sleep efficiency (r = -0.127, p = 0.592), light sleep percentage (r = 0.024, p = 0.921), deep sleep percentage (r = 0.181, p = 0.444) or sleep latency (rs = 0.384, p = 0.094). The app slightly and nonsignificantly overestimated sleep efficiency by 0.12% (95% confidence interval [CI] -4.9 to 5.1%, p = 0.962), significantly underestimated light sleep by 27.9% (95% CI 19.4-36.4%, p < 0.0001), significantly overestimated deep sleep by 11.1% (CI 4.7-17.4%, p = 0.008) and significantly overestimated sleep latency by 15.6 min (CI 9.7-21.6, p < 0.0001). Epochwise comparison showed low overall accuracy (45.9%) due to poor interstage discrimination, but high accuracy in sleep-wake detection (85.9%). The app had high sensitivity but poor specificity in detecting sleep (89.9% and 50%, respectively). CONCLUSIONS Our study shows that the absolute parameters and sleep staging reported by the Sleep Time app (Azumio, Inc.) for iPhones correlate poorly with PSG. Further studies comparing app sleep-wake detection to actigraphy may help elucidate its potential clinical utility. COMMENTARY A commentary on this article appears in this issue on page 695.

REM behavior disorder in myotonic dystrophy type 2

A 63-year-old woman with myotonic dystrophy type 2[1][1] and obstructive sleep apnea by polysomnography, not on medications traditionally known to cause REM behavior disorder (RBD), had dream-enacting behavior (DEB). Overnight continuous positive airway pressure titration captured an episode of DEB

Sleep disorders in neuromuscular diseases.

Sleep disorders are common in patients with neuromuscular diseases, but are often overlooked. Recognizing and treating issues relating to sleep disturbances improves the quality of life for these patients. This article provides an overview of the sleep dysfunction that occurs in neuromuscular diseases, of which the most common is sleep-disordered breathing. In addition, the current literature is reviewed to provide primary care physicians, sleep specialists, neurologists, and neuromuscular specialists with information on available diagnostic and treatment modalities.

Sleep disordered breathing and other sleep dysfunction in myotonic dystrophy type 2.

To the Editor, Myotonic dystrophy type 2 (DM2) is clinically and genetically distinct from myotonic dystrophy type 1 (DM1) [1–4]. Sleep disordered breathing (SDB) is well known in DM1 [2,3] but our observations of SDB and other sleep dysfunction in six patients with DM2 are unique. Table 1 summarises the major clinical and polysomnographic (PSG) data. Genetic testing (CCTG expansion mutation of intron 1 of zinc finger 9 gene on chromosome 3) was positive in patients 3–6. Patients 1 and 2 were genetically ruled out for DM1, but when genetic testing for DM2 became available, they declined. All patients had proximal muscle weakness, percussion myotonia, repeated nocturnal awakenings and daytime hypersomnolence. Four patients had snoring and one had dream enacting behaviour (DEB) [5]. Electromyographic findings were consistent with proximal myopathy and myotonia. PSG showed increased arousals, decreased sleep efficiency, alpha-delta sleep in patients 1 and 2, obstructive sleep apnea (OSA) in patients 3–6, and paradoxical breathing during rapid

Intensified hypnic jerks: a polysomnographic and polymyographic analysis.

Purpose: To analyze the nature and propagation of muscle bursts in patients presenting with intensified hypnic jerks and sleep onset insomnia. Methods: We obtained polymyographic recordings from cranially and spinally innervated muscles during polysomnographic study in 10 subjects presenting with repeated jerking movements at sleep onset, anxiety and sleep onset insomnia. One subject also had daytime polymyography during relaxed wakefulness and drowsiness as well as back-averaging of the EEG preceding the muscle bursts. Results: We observed 4 patterns of muscle propagation: synchronous and symmetrical patterned muscle bursts between the two sides and agonist-antagonist muscles similar to those noted in audiogenic startle reflex, reticular reflex myoclonus, dystonic myoclonus, and pyramidal myoclonus with rostrocaudal propagation of muscle bursts. Conclusion: Hypnic jerks are physiological phenomena which may be accentuated and repeated and may be of several physiological subtypes.

Increasing off-time improves sleep-disordered breathing induced by vagal nerve stimulation.

Vagal nerve stimulation (VNS) has been reported to adversely impact breathing in sleep. While continuous positive airway pressure is often employed to treat these patients, little data exist on the effects of adjusting various settings on VNS-induced sleep-disordered breathing. We describe a patient in whom increasing off-time caused resolution of VNSinduced arterial oxygen desaturations in sleep, which we believe is a novel observation.

Continuous Spike and Wave in Slow-Wave Sleep in a Patient With Rett Syndrome and in a Patient With Lhermitte-Duclos Syndrome and Neurofibromatosis 1

Continuous spike and wave in slow-wave sleep (CSWS) is an electroencephalographic (EEG) pattern characterized by generalized spike-wave discharges occurring for at least 85% of non–rapid eye movement (non-REM) sleep, with marked attenuation during rapid eye movement (REM) sleep. It has been described in a large number of structural and nonstructural neurologic conditions and is associated with epilepsy, behavioral disturbances, and severe neuropsychiatric impairment. We describe continuous spike and wave in slow-wave sleep in 2 patients (one with Rett syndrome and the other with Lhermitte-Duclos syndrome). To our knowledge, continuous spike and wave in slow-wave sleep has not been previously described in these conditions.

Complex sleep behavior in a patient with obstructive sleep apnea and nocturnal hypoglycemia: A diagnostic dilemma

Abnormal behavior in sleep has multiple potential etiologies including untreated obstructive sleep apnea (OSA), REM behavior disorder (RBD), nocturnal seizures and disorders of partial arousal. These can be differentiated by characteristic clinical, polysomnography (PSG) and electroencephalography (EEG) findings [1]. We describe a patient with different types of abnormal behavior in sleep, caused by OSA and hypoglycemia.

The therapeutic dilemma of vagus nerve stimulator-induced sleep disordered breathing.

Intermittent vagus nerve stimulation (VNS) can reduce the frequency of seizures in patients with refractory epilepsy, but can affect respiration in sleep. Untreated obstructive sleep apnea (OSA) can worsen seizure frequency. Unfortunately, OSA and VNS-induced sleep disordered breathing (SDB) may occur in the same patient, leading to a therapeutic dilemma. We report a pediatric patient in whom OSA improved after tonsillectomy, but coexistent VNS-induced SDB persisted. With decrease in VNS output current, patients SDB improved, but seizure activity exacerbated, which required a return to the original settings. Continuous positive airway pressure titration was attempted, which showed only a partial improvement in apnea–hypopnea index. This case illustrates the need for clinicians to balance seizure control and SDB in patients with VNS.

Movement Disorders in Sleep

Normal and abnormal movements in sleep have been a source of both great academic interest and clinical confusion. Nocturnal head banging (jactatio capitis nocturna) was one of the earliest-described sleep-related movement disorders, having first been mentioned in 1811. Since Manoia’s initial classification of abnormal movements in sleep as a separate category of sleep disturbances 90 years ago, a lot of progress has been made in the field. Several investigators have contributed to our understanding of these phenomena, which include rhythmic movements in sleep, hypnic jerks, propriospinal myoclonus, periodic limb movements in sleep, catathrenia, and phasic muscle movements in rapid eye movement (REM) sleep. This chapter provides a brief chronological account of discoveries and research in the field of sleep-related movement disorders.