Characteristics of Sleep and Autonomic Activity in Active Older Adults Based on Metabolic Age: A Comparative Case Study

Background: The balance of autonomic nervous system activity and its relationship with body composition, sleep quality, and activities of daily living among older people is still unclear. Purpose: This comparative case study examined the characteristics of body composition, sleep quality, and autonomic nerve activity in active older adults with a younger body age-calculated from age trends in body composition and basal metabolic rate. Methods: We selected two cases with a metabolic age younger than their actual age. They had good sleep quality, no sarcopenia, strong muscle and grip strength, and balanced autonomic nervous system activity. They were compared with two other age- and gender-matched cases, who had poor sleep quality, unbalanced autonomic nervous system activity, and had a physical age closer to their actual age. Results: Older adults with more muscle mass and higher basal metabolism were younger than their actual age, had a better sleep status, and had a good balance of autonomic nervous activity during exercise stimulation. They also had lower percentages of body and visceral fat and higher percentages of body water. Conclusion: Two cases had a metabolic age younger than their actual age were found to be much younger than their actual age. However, the older adults with normal muscle mass and basal metabolic rate had poor sleep status and no sympathetic hyperactivity during exercise simulation.