A new study published in the Journal of Clinical Endocrinology and Metabolism (JCEM) suggests that people who habitually stay up late have a higher risk of diabetes, metabolic syndrome, and sarcopenia than those who go to bed early and wake up early, even if the total amount of sleep is the same. The study included 1,620 adults aged 47-59 years from Korean genomic and epidemiological studies, classified according to sleep type or individual physiological rhythm preference/behavior, as well as biological rhythms corresponding to the external circadian cycle, and assessed using the morningness-eveningness questionnaire (MEQ). MEQ) assessment. All participants were also subjected to an oral glucose tolerance test and a DEXA examination to assess body composition. Results showed that 29.6% of participants were morning-type, 5.9% were night-type, and 64.5% had both sleep types. After correcting for potential confounders, the night type was significantly associated with an increased risk of diabetes (OR=1.73; 95% CI, 1.01-2.95), metabolic syndrome (OR=1.74; 95% CI, 1.05-2.87) and sarcopenia (OR=3.16; 95% CI, 1.36-7.33) compared to the morning type. The researchers also found a gender difference in this increased risk. Compared with those who went to bed early and woke up early, night owls had a 73% and 74% increased risk of diabetes and metabolic syndrome, respectively, and more than twice the risk of sarcopenia. For men, nocturnal phenotype was associated with both diabetes (OR=2.98; 95% CI, 1.39-6.39) and sarcopenia (OR=3.89; 95% CI, 1.33-11.33), while for women nocturnal phenotype was associated only with metabolic syndrome (OR=2.22; 95% CI, 1.11-4.43). The researchers said, “Regardless of lifestyle, compared to early sleepers and early risers, frequent late-nighters had a high risk of diseases such as diabetes and sarcopenia, which may be related to the fact that night owls typically have poorer sleep quality and often have unhealthy habits such as smoking, late-night snacking and sedentary lifestyle. “Although people with the night type are generally younger compared to the morning type, they also usually have higher levels of body fat and triglycerides. Women belonging to the morning type have more abdominal fat. Considering that a large number of young people are night-types, the metabolic risk posed to them by the reversal of physiological rhythms is an important health concern.