Journal of sleep researchJul 28, 2026

Daytime Changes in Attention and Brain Activity Linked to Vulnerability

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Aug 3, 2026

Abstract

In a study of 48 healthy adults, vulnerable individuals showed broader increases in delta, theta, and beta brain wave activity under elevated sleep pressure.

Daytime vigilance fluctuations vary significantly between individuals.
Participants were classified into vulnerable and resilient groups based on their performance on a vigilance task.
Vulnerable individuals experienced a decline in vigilance linked to increased brain wave activity across various regions due to sleep pressure.
A post-lunch nap reversed this decline in vulnerable individuals, indicating the potential for recovery from accumulated sleep pressure.
Resilient individuals managed to maintain stable vigilance by enhancing specific brain activity rather than experiencing widespread changes.

Simplified

While the significance of adequate nocturnal sleep for daytime vigilance is well recognised, substantial inter-individual variation exists in vigilance fluctuations across the day. In a laboratory-controlled setting, we examined individual differences in daytime vigilance fluctuations and dissociated the contributions of sleep pressure and circadian rhythm. With 48 healthy adults, we recorded resting-state electroencephalogram (EEG) activity and subsequent performance on the Psychomotor Vigilance Task (PVT) in the morning (MOR), the afternoon without napping (NN) and the afternoon after napping (NP). Based on the changes in PVT performance between MOR and NN, participants were divided into a vulnerable group (24 individuals) and a resilient group (24 individuals). From MOR to NN, vulnerable individuals exhibited broader increases in delta, theta, beta1 and beta2 power across distributed regions under elevated sleep pressure. These broad spectral changes contributed to a progressive decline in vigilance, which can be reversed by a post-lunch nap to dissipate accumulated sleep pressure. In contrast, resilient individuals maintained stable vigilance by selectively enhancing frontal theta or beta activity. These distinct neural characteristics may serve as biomarkers for predicting fatigue vulnerability and guiding personalised countermeasures in safety-critical occupations.

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Daytime Changes in Attention and Brain Activity Linked to Vulnerability

Abstract

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