Virginia Thornley, M.D.

Neurologist, Epileptologist

March 6, 2019

What is the impact of sleep on cognition of shift workers?

Those with circadian misalignment such as night shift workers are most affected in terms of sustained attention, visual-motor performance and processing of information(1).

One study sought to clarify the relationship of circadian cycle misalignment with cognition. It found that on the first night of shift work, attention is markedly impaired which improves after the same schedule is followed. This did not hold true for areas in visual-motor or cognitive throughput. Cognitive throughput means the summation of data going through a network.

Declarative memory is stable while attention was greatly impacted. This may be because memory is not impacted by areas where the sleep-wake cycle is important.

It is thought that there is increased GABAergic tone at night which could depress cognition. The natural circadian rhythm allows for maximum cognitive abilities during the daytime. . This is when we get our peak performance. The worse time for vulnerabilities in cognition occurred in the hours between 4-6am(1).

The neurobiology is thought that lack of sleep at night affects the conduction of nerves including the local potential field which affects neuronal activity. This results in reduced reaction time and speed for visual motor performance and tasks requiring sustained attention (2).