INTRODUCTIONChronic insomnia is associated with many physical and psychiatric illnesses, and its underlying aetiology needs to be identified in order to achieve safe and effective treatment. Obstructive sleep apnoea (OSA) and periodic limb movement disorder (PLMD) are common primary sleep disorders that can lead to chronic insomnia. Patients with these conditions are evaluated using polysomnography (PSG).

METHODSThe PSG records of 106 patients with chronic insomnia who presented to a multidisciplinary sleep clinic in Singapore over a five-year period were reviewed. To examine the utility of PSG in the evaluation of chronic insomnia, the clinical diagnoses of the patients before and after the sleep studies were compared.

RESULTSAmong the 106 patients, 69 (65.4%) were suspected to have primary sleep disorders based on clinical history and examination alone. Following PSG evaluation, 42.5% and 4.7% of the study population were diagnosed with OSA and PLMD, respectively. OSA was found in 35.9% of the 39 patients who had underlying psychiatric conditions.

CONCLUSIONThis study illustrates that many patients with chronic insomnia have underlying primary sleep disorders. It also highlights the danger of attributing chronic insomnia in psychiatric patients to their illness, without giving due consideration to other possible aetiologies. Clinicians should maintain a high index of suspicion for the presence of other aetiologies, and make timely and targeted referrals for sleep studies where appropriate.

Adult ; Age Factors ; Aged ; Aged, 80 and over ; Female ; Humans ; Male ; Medical Records ; Middle Aged ; Nocturnal Myoclonus Syndrome ; diagnosis ; Polysomnography ; methods ; Retrospective Studies ; Severity of Illness Index ; Singapore ; Sleep Apnea, Obstructive ; diagnosis ; Sleep Initiation and Maintenance Disorders ; therapy ; Sleep Wake Disorders ; diagnosis ; Treatment Outcome ; Young Adult

Background: Fatigue is pervasive, under-reported, and potentially deadly where flight operations are concerned. The aviation industry appears to lack a standardized, practical, and easily replicable protocol for fatigue risk assessment which can be consistently applied across operators.AimOur paper sought to present a framework, supported by real-world data with subjective and objective parameters, to monitor aircrew fatigue and performance, and to determine the safe crew configuration for commercial airline operations. Methods: Our protocol identified risk factors for fatigue-induced performance degradation as triggers for fatigue risk and performance assessment. Using both subjective and objective measurements of sleep, fatigue, and performance in the form of instruments such as the Karolinska Sleepiness Scale, Samn-Perelli Crew Status Check, Psychomotor Vigilance Task, sleep logs, and a wearable actigraph for sleep log correlation and sleep duration and quality charting, a workflow flagging fatigue-prone flight operations for risk mitigation was developed and trialed. Results: In an operational study aimed at occupational assessment of fatigue and performance in airline pilots on a three-men crew versus a four-men crew for a long-haul flight, we affirmed the technical feasibility of our proposed framework and approach, the validity of the battery of assessment instruments, and the meaningful interpretation of fatigue and work performance indicators to enable the formulation of safe work recommendations. Conclusion A standardized occupational assessment protocol like ours is useful to achieve consistency and objectivity in the occupational assessment of fatigue and work performance.