Researchers from Auckland, New Zealand, have published a study in Frontiers in Nutrition showing that women who stay up late – often called “night owls” – face a range of metabolic disadvantages compared with those who rise early.
Study design and participants
The investigators followed 287 healthy women aged 18 to 45, including 130 Pacific‑heritage participants and 157 of European descent. Using the Munich Chronotype Questionnaire (MCTQ), participants were classified as morning, intermediate, or evening (night‑owl) types based on their typical sleep‑wake schedule.
Women who usually slept from 11 p.m. to 8 a.m. were labeled intermediate, while those who went to bed later and woke up later fell into the evening category. Over five non‑consecutive days – three weekdays and two weekend days – each participant recorded every food and beverage consumed.
Measurements beyond BMI
Instead of relying solely on body‑mass index, the team used dual‑energy X‑ray absorptiometry (DXA) scans to assess total body fat and its distribution, especially around the waist and hips. Blood samples were taken to measure glucose, cholesterol, triglycerides, insulin, and appetite‑related hormones such as leptin and ghrelin.
Key findings
Night‑owl women ate fewer nutrient‑dense foods and consumed a larger share of their daily calories in the evening. This eating pattern correlated with a higher body‑fat percentage, greater waist‑to‑hip fat storage, and an elevated risk of obesity.
Even though total calorie intake was similar across all chronotypes, night owls showed higher body‑mass index (BMI) and more overall body fat than morning types. Blood‑test results revealed higher insulin and triglyceride levels, lower “good” HDL cholesterol, elevated leptin (a hormone linked to fat storage), and reduced ghrelin (the hunger‑signaling hormone).
Overall, night‑owl participants performed worse on almost every metabolic metric measured: higher BMI, more abdominal fat, poorer lipid profiles, and lower intake of fiber, essential vitamins, and minerals.
Implications for families and health
The study underscores the importance of sleep timing for metabolic health, a concern that resonates with families seeking to protect the well‑being of their children and themselves. Aligning sleep schedules with natural daylight may help improve diet quality, hormone balance, and long‑term health outcomes.
While the research focused on women in New Zealand, the findings are relevant to anyone in the United States who struggles with late‑night habits. Health professionals and parents alike may consider encouraging earlier bedtimes as part of a broader strategy to promote healthier eating patterns and reduce the risk of obesity and related diseases.
Original reporting: Texarkana Gazette — read the source article.
