Reduced Tolerance to Night Shift in Chronic Shift Workers
Summary
This study combined field and laboratory experiments to test how night shifts affect the body’s internal regulation of activity patterns, known as fractal regulation (FR). Compared to non-shift workers, chronic shift workers showed more disrupted and random activity rhythms during night shifts, and these disturbances persisted for up to two days afterward. The laboratory results confirmed that chronic shift workers were less resilient to circadian misalignment than non-shift workers, and those who began shift work later in life experienced even greater disruption.
Why It Matters For Night Shift Workers and Night Owls
This study shows that the body does not “get used to” night shifts — in fact, long-term shift work may make it harder to adapt over time. Chronic night workers had weaker circadian control, leaving them more vulnerable to fatigue, irregular sleep, and poor recovery. For individuals, this means that night shifts may feel progressively harder with years of exposure. For employers, the findings emphasize the need for protective scheduling — such as stable patterns, built-in recovery days, and supportive strategies like light management or naps — to help preserve workers’ long-term health and tolerance.
Notes
Mechanistic/physiology focus.