Under normal circumstances, the daily rhythm of melatonin secretion causes concentrations in the blood to be “high during the nighttime and nearly undetectable during the daytime, ” says the report in The Journal of Clinical Endocrinology & Metabolism.
وفي الوقت نفسه ،‏ كشفت فحوص الدم ان هؤلاء المقيمين المسنين لديهم مستويات منخفضة من الهرمون ميلاتونين .‏