Genetic Basis and Classification
Chronotype variation is primarily driven by clock gene polymorphisms. For the PER3 gene VNTR polymorphism, carriers of the 5-repeat allele have been reported to show a strong morning preference, while 4-repeat carriers tend toward eveningness. Specific CRY1 mutations extend the circadian period and are known to be associated with extreme evening chronotypes. Clear morning types and clear evening types are both minorities, with most people falling somewhere in between. Age produces significant shifts: adolescence drives a strong evening shift, while aging gradually returns individuals toward morningness. The Munich Chronotype Questionnaire (MCTQ) is a widely used instrument that assesses chronotype in a standardized way from sleep timing on free days, with the mid-sleep point serving as the primary indicator.
Social Jet Lag and Cognitive Function
Social jet lag describes the discrepancy between biological sleep timing and socially mandated schedules. When evening-type individuals are forced to wake early, their biological clock registers deep night while they attempt complex cognitive tasks. In this misaligned state, reaction times lengthen and attentional lapses become more frequent. People with larger social jet lag have also been reported to show lower academic performance and workplace productivity. The prefrontal cortex, which matures last and is sensitive to circadian disruption, shows reduced activation during non-optimal times. Testing during one's biological peak yields scores that more accurately reflect true cognitive capacity.
Optimizing Test Timing
To get the most out of a Bench test, selecting a time aligned with your chronotype matters. Morning types tend to be at their best in the first few hours after waking (typically 8-10 AM), while evening types tend to peak in the afternoon to evening (typically 4-8 PM). To determine your chronotype, record your sleep onset and natural wake times on free days without alarms for two weeks, then calculate the midpoint between them (your mid-sleep point). An earlier mid-sleep point suggests a morning-leaning chronotype, and a later one an evening-leaning chronotype. Your Bench score patterns across different testing times can also reveal chronotype: consistent underperformance in morning sessions with improvement in evening sessions indicates evening chronotype. Aligning test sessions with your biological peak reduces a major source of score variability.