Growth Factor Method
Scientific Foundation

The relationships behind GFM are grounded in published research.

GFM uses established findings from sleep science, autonomic physiology, and cognitive research to inform individualized interpretation. The biometric-cognitive relationships we apply are supported by meta-analyses across dozens of laboratories, hundreds of studies, and thousands of subjects.

Evidence Summary

Cognitive Domains: Effect Sizes and Citations

Five physiological systems shape four core cognitive domains. The relationships are documented across decades of literature. Sleep deprivation produces the largest effect on vigilance, executive functions follow. The effect sizes below represent the strongest evidence for each.

Domain-Level Effect Sizes

Sleep deprivation's documented effect on each cognitive domain

Cognitive Domain Effect Size Primary Citations Defensibility
VIGILANCE
Alertness (PVT)		 d = -0.776
LARGE		 Lim & Dinges, 2010
(70 studies)
Strongest
EXECUTION
Attention (MOT)		 d = 0.47
MEDIUM-LARGE		 Lim & Dinges, 2010
Thayer et al., 2009
Strong
ENCODING
Working Memory (N-Back)		 d = 0.40
MEDIUM		 Lim & Dinges, 2010
Chee & Chuah, 2008
Strong
INHIBITION
Impulse Control (Go/No-Go)		 d = 0.35
SMALL-MEDIUM		 Lim & Dinges, 2010
Laborde et al., 2018
Moderate-Strong
Underlying Capacity Modifier
VO2 MAX
Cognitive Capacity Modifier		 OR 8.94
for WM dysfunction		 Scientific Reports, 2024
Zeigler et al., 2013
Strong
By The Numbers

Research Foundation

70+
Studies in Primary
Meta-Analysis
147
Cognitive Tests
Analyzed
160+
Studies Validating
MOT Task
1,400+
Participants in VO2 Max
Study
Key Citations

Primary Sources

Lim, J., & Dinges, D. F. (2010)
A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological Bulletin, 136(3), 375-389.
Meta-analysis of 70 studies examining sleep restriction effects on cognition. Established effect sizes for Vigilance (d = -0.776), Execution/Attention (d = 0.47), Encoding/Working Memory (d = 0.40), and Inhibition (d = 0.35). The foundational citation for GFM's sleep-cognition predictions.
Thayer, J. F., Hansen, A. L., Saus-Rose, E., & Johnsen, B. H. (2009)
Heart rate variability, prefrontal neural function, and cognitive performance: The neurovisceral integration perspective. Annals of Behavioral Medicine, 37(2), 141-153.
Neurovisceral integration model linking HRV to prefrontal function and executive control. Establishes HRV as index of cognitive flexibility, attention, and working memory capacity.
Pylyshyn, Z. W., & Storm, R. W. (1988)
Tracking multiple independent targets: Evidence for a parallel tracking mechanism. Spatial Vision, 3(3), 179-197.
Original Multiple Object Tracking (MOT) paradigm developed at University of Western Ontario. Validated in 160+ subsequent studies. GFM's primary measure of attentional execution capacity.
Wang, Y., Chen, S., Zhang, Y., et al. (2024)
Associations between cardiorespiratory fitness and executive function in Chinese adolescents. Scientific Reports, 14, Article 21007.
Cross-sectional analysis (1,245 adolescents) showing those with VO2 max P75. Establishes VO2 max as cognitive capacity modifier.
GFM's Contribution

We don't discover relationships.
We operationalize them.

The sleep-cognition relationship has been established for decades. The HRV-prefrontal connection is foundational neuroscience. The VO2 max-cognitive capacity link is documented across hundreds of subjects.

What GFM does is make these relationships actionable.

We translate "sleep restriction impairs working memory with effect size d = 0.40" into "Your encoding capacity is constrained today — only 12% deep sleep last night. Defer complex learning until tomorrow."

We transform "HRV correlates with executive function" into "Your execution capacity is well-supported right now — HRV peaked, parasympathetic dominance. Schedule deep work sessions."

GFM's innovation isn't the underlying science — it's the synthesis. We combine established relationships into personalized, constraint-specific assessments calibrated to your unique biology.

Still skeptical? Read the full research base →
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GFM is built on decades of peer-reviewed research across sleep science, cognitive neuroscience, and autonomic physiology. Every claim we make is grounded in published literature. Below are the primary sources underpinning our forecasting model.

Sleep & Cognitive Performance
Primary Meta-Analysis: Sleep Deprivation and Executive Function
Lim, J., & Dinges, D. F. (2010). A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological Bulletin, 136(3), 375-389.
Sleep Architecture and Memory Consolidation
Rasch, B., & Born, J. (2013). About sleep's role in memory. Physiological Reviews, 93(2), 681-766.
Sleep Quality and Attentional Performance
Alhola, P., & Polo-Kantola, P. (2007). Sleep deprivation: Impact on cognitive performance. Neuropsychiatric Disease and Treatment, 3(5), 553-567.
Heart Rate Variability & Cognition
HRV and Executive Function: Systematic Review
Forte, G., Favieri, F., & Casagrande, M. (2019). Heart rate variability and cognitive function: A systematic review. Frontiers in Neuroscience, 13, 710.
Parasympathetic Activity and Prefrontal Cortex Coupling
Thayer, J. F., Ahs, F., Fredrikson, M., Sollers, J. J., & Wager, T. D. (2012). A meta-analysis of heart rate variability and neuroimaging studies. Neuroscience & Biobehavioral Reviews, 36(2), 747-756.
Resting Heart Rate and Cognitive Performance
Britton, A., Singh-Manoux, A., Hnatkova, K., Malik, M., Marmot, M. G., & Shipley, M. (2008). The association between heart rate variability and cognitive impairment in middle-aged men and women. Neuroepidemiology, 31(2), 115-121.
Multiple Object Tracking (MOT)
Original MOT Research (Foundational Paper)
Pylyshyn, Z. W., & Storm, R. W. (1988). Tracking multiple independent targets: Evidence for a parallel tracking mechanism. Spatial Vision, 3(3), 179-197.
MOT and Attentional Capacity
Cavanagh, P., & Alvarez, G. A. (2005). Tracking multiple targets with multifocal attention. Trends in Cognitive Sciences, 9(7), 349-354.
MOT as Executive Function Measure
Drew, T., Horowitz, T. S., Wolfe, J. M., & Vogel, E. K. (2011). Delineating the neural signatures of tracking spatial position and working memory during attentive tracking. Journal of Neuroscience, 31(2), 659-668.
Circadian Rhythms & Performance
Time-of-Day Effects on Cognitive Performance
Schmidt, C., Collette, F., Cajochen, C., & Peigneux, P. (2007). A time to think: Circadian rhythms in human cognition. Cognitive Neuropsychology, 24(7), 755-789.
Autonomic Nervous System and Cognitive Windows
Laborde, S., Mosley, E., & Thayer, J. F. (2017). Heart rate variability and cardiac vagal tone in psychophysiological research. Frontiers in Psychology, 8, 213.
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