Existing chronotype models focus on circadian phase preferences, providing limited insight into how these preferences translate into everyday psychological functioning. Especially, they overlook individual differences in daily energy levels and the effectiveness of their regulation, which may explain why people with similar biological rhythms differ in adaptability and well-being. The present study aimed to develop and empirically validate a theoretically grounded psychological framework of chronotype - the Biopsychological Owls and Larks Typology (BOLT) - which conceptualizes chronotype as a system of energy regulation defined by two dimensions: overall energy level and regulatory effectiveness. The study included 1426 Polish adults aged 20-60 years who completed the Biopsychological Owls and Larks Typology Scale (BOLTS), the Morningness-Eveningness Stability Scale improved, and standardized measures of depression, anxiety, life satisfaction, and temperament traits. Factor analyses supported a four-profile structure comprising hardy larks, vulnerable larks, overactive owls, and neurotic owls. Measurement invariance across two independent samples was confirmed. The identified profiles showed distinct and theoretically meaningful patterns of associations with affective and temperamental variables, ranging from highly adaptive to maladaptive functioning. These findings support the BOLT model and suggest that chronotype is best understood as a biopsychological system of energy regulation rather than solely as a timing preference.
Gorgol-Waleriańczyk et al. (Mon,) studied this question.