The Differential Effects of Regular Shift Work and Obstructive Sleep Apnea on Sleepiness, Mood and Neurocognitive Function

STUDY OBJECTIVES

To assess whether poor sleep quality experienced by regular shift workers and individuals with obstructive sleep apnea (OSA) affects neurobehavioral function similarly, or whether the different etiologies have distinct patterns of impairment.

METHODS

Thirty-seven shift workers (> 24 hours after their last shift), 36 untreated patients with OSA, and 39 healthy controls underwent assessment of sleepiness (Epworth Sleepiness Scale [ESS]), mood (Beck Depression Index, State Trait Anxiety Inventory [STAI], Profile of Mood States), vigilance (Psychomotor Vigilance Task [PVT], Oxford Sleep Resistance Test [OSLER], driving simulation), neurocognitive function (Logical Memory, Trails Making Task, Digit Span Task, Victoria Stroop Test) and polysomnography.

RESULTS

Sleepiness (ESS score; median, interquartile range) did not differ between the OSA (10.5, 6.3-14) and shift work (7, 5-11.5) groups, but both had significantly elevated scores relative to the control group (5, 3-6). State anxiety (STAI-S) was the only mood variable that differed significantly between the OSA (35, 29-43) and shift work (30, 24-33.5) groups, however both demonstrated several mood deficits relative to the control group. The shift work and control groups performed similarly on neurobehavioral tasks (simulated driving, PVT, OSLER and neurocognitive tests), whereas the OSA group performed worse. On the PVT, lapses were significantly greater for the OSA group (3, 2-6) than both the shift work (2, 0-3.5) and control (1, 0-4) groups.

CONCLUSIONS

Shift workers and patients with OSA had similar sleepiness and mood deficits relative to healthy individuals. However, only the patients with OSA showed deficits on vigilance and neurocognitive function relative to healthy individuals. These findings suggest that distinct causes of sleep disturbance likely result in different patterns of neurobehavioral dysfunction.

Pulmonary mechanoreceptors in the dipnoi lungfish Protopterus and Lepidosiren

Pulmonary mechanoreceptors in the dipnoi lungfish Protopterus aethiopicus and Lepidosiren paradoxa were identified and characterized both in vivo and in vitro. Both slowly adapting receptors (SAR) and rapidly adapting receptors (RAR) were found, with the majority of receptors being of the slowly adapting type. The SAR discharged during inflation once their threshold volume was exceeded, and this activity persisted during prolonged lung inflation. For most of the SAR, interaction between the rate of inflation and lung volume was involved in setting the firing rate of the receptor. Increase in intrapulmonary carbon dioxide partial pressure decreased the activity of the SAR during sustained inflation at a constant intrapulmonary pressure. The RAR also discharged during inflation once the threshold volume was exceeded. However, in contrast to the SAR, the RAR became silent within 1.5 - 15 s after the end of inflation. The activity of these receptors during inflation was influenced predominantly by the rate and influenced little by the volume of inflation. According to these observations, the behavior of lungfish pulmonary mechanoreceptors closely resembles that of pulmonary mechanoreceptors in amphibians but differs from that of mechanoreceptors in the swim bladder of teleosts.