The cognitive clouding that plagues roughly 60% of perimenopausal women may have identifiable roots that extend beyond hormonal fluctuations alone. This insight matters because 'brain fog'—characterized by memory lapses and attention difficulties—can significantly impact professional performance and daily functioning during a critical life stage when many women are at career peaks. Analysis of 208 perimenopausal women aged 41-60 reveals that sleep disturbances emerge as the strongest predictor of subjective cognitive symptoms, followed by psychological factors including anxiety, depression, and stress levels. The research employed both traditional regression analysis and machine learning approaches to identify which among 13 potential factors most strongly correlate with memory and attention complaints. Sleep quality demonstrated the most robust association with cognitive symptoms, suggesting that the widely reported brain fog may be less about direct hormonal effects on cognition and more about the cascade of sleep disruption that hormonal changes trigger. This finding challenges the common assumption that cognitive symptoms are an inevitable direct consequence of estrogen decline. The implications for midlife women are significant: addressing sleep hygiene and managing psychological symptoms may offer more immediate cognitive relief than hormone replacement therapy alone. However, the study's reliance on self-reported symptoms rather than objective cognitive testing limits definitive conclusions about actual cognitive performance. The cross-sectional design also prevents establishing whether poor sleep causes brain fog or vice versa, though extensive sleep research suggests the former is more likely.