Fatigue in air traffic control (ATC) is a critical safety concern, yet the influence of socio-demographic factors such as age and gender remains underexamined. This study investigated how age and gender shape both subjective and objective fatigue in air traffic controllers (ATCOs) across operational shifts. Data were collected from 73 participants at a Scandinavian Area Control Center. Subjective sleepiness was assessed using the Stanford Sleepiness Scale (SSS), and objective fatigue was measured using a 3-minute Psychomotor Vigilance Task (PVT-B), administered at three timepoints per shift (pre, mid, post). Linear mixed models were used to analyze the effects of age (dichotomized at the median: \(\le \) 45 vs. \(\ge \) 46 years) and gender on fatigue outcomes. Results showed that older ATCOs exhibited slower reaction times (RT), indicating greater objective fatigue, while reporting lower self-rated sleepiness (particularly during night shifts) than their younger counterparts. Younger participants, in contrast, showed faster RTs and longer on-shift sleep, yet reported higher self-rated sleepiness at specific timepoints. Gender differences were less consistent but evident in sustained attention: males showed systematically faster RTs and longer on-shift sleep during night shifts. No overall gender effect was found in self-rated sleepiness, although isolated timepoint differences emerged. Interactions between age, gender, shift type, and timepoint revealed context-specific fatigue patterns. These findings highlight the multidimensionality of fatigue and suggest that age and gender shape fatigue in nuanced, time-dependent ways. Integrating socio-demographic variability into fatigue risk management may support the development of more adaptive and equitable shift designs and countermeasure strategies in safety-critical settings.
