New study highlights individual factors behind stress responses to night work

In a new study published in the Journal of Sleep Research, researchers at Uppsala University's Faculty of Pharmacy have investigated how biological and psychological factors interact in sleep deprivation, with a particular focus on individual variations rather than group differences. This work provides important knowledge about how night work may be linked to short-term stress-related changes in the brain.

One of the factors examined was the personality trait neuroticism, a well-established trait present in all individuals that reflects how strongly people tend to respond to stress and emotional challenges. Neuroticism exists along a continuum in everyone and is not a measure of mental illness. While average levels of neuroticism can differ slightly between genders, the trait itself is relevant for understanding individual differences in stress responses. Previous research has linked higher levels of neuroticism both to increased stress reactivity and to greater attentiveness to health and environmental cues.

The study included 54 healthy young adult women aged 21–33 years. Participants completed both a night of normal sleep and a night of total sleep deprivation to simulate a night shift. Blood samples were collected the following morning to measure levels of phosphorylated tau protein, p-Tau181, a biomarker previously studied in relation to neurodegenerative processes in other contexts.

“After one night of being awake, we observed a very small increase in p-Tau181 among participants reporting higher stress sensitivity. It is important to emphasize that the change was minimal and not clinically meaningful in itself," says Diana Nôga, Senior researcher and first author of the study.

No clear association was found between estradiol levels and changes in the biomarker p-Tau181 following the simulated night shift. The study cannot determine whether similar associations would be observed in other populations, such as men, older adults, or individuals with long-term night-work experience. The inclusion of women only should therefore be understood as a methodological choice, not as evidence that women are inherently more vulnerable to night work.

“Our results should not be interpreted as meaning that certain groups are more vulnerable to night work than others. Rather they suggest that biological responses to sleep loss are shaped by a combination of psychological, social, and biological factors that vary between individuals. Previous research also shows that measures such as sufficient rest periods, opportunities for recovery, predictable routines, and organizational responsibility for the work environment are central to reducing the strain associated with night work,” says Christian Benedict, Professor of Pharmacology.

The study contributes to a growing body of knowledge on how night work affects the body in the short term. From a gender-equality and occupational health perspective, the results underscore the importance of designing night work with attention to individual needs and recovery—rather than framing gender or personal characteristics as inherent risk factors.

Text: Magnus Alsne, photo: Mikael Wallerstedt a o