Effect of Meal Glycemic Index and Meal Frequency on Glycemic Variability During Night Shifts
Summary
Summary
This randomized cross-over study tested female nurses working real night shifts. Each nurse completed three 3-day periods (in random order) during nights: no meal, low-glycemic-index (low-GI) yogurt-based meal(s), or high-GI meal(s). Some nurses had one night-shift meal; others had three—so the study could separate meal frequency (1 vs 3) from meal type (low vs high GI). Continuous glucose monitors tracked blood sugar during the night shift (21:30–07:00), the following morning (07:00–13:00), and over 24 hours.
What happened:
- High-GI meals caused bigger spikes and more variability in blood sugar at night, the next morning, and often across 24 h, compared with no meal.
- Low-GI meals were about the same as fasting on almost all stability measures (one small exception at night with three low-GI snacks). In some analyses, low-GI even looked better than fasting the next morning/over 24 h.
- Meal frequency (1 vs 3) didn’t independently affect glucose control once GI was considered.
Bottom line: At night, what you eat mattered more than how often you eat.
Why It Matters For Night Shift Workers and Night Owls
If you need to eat on nights, choose low-GI options—they kept blood sugar as steady as fasting in this study, while high-GI choices (sugary drinks, sweets, white bread) made it swing more at night and into the next morning. Whether you eat once or three times mattered far less than keeping the meal low-GI. Practical takeaway: plan small, low-GI night snacks (think yogurt without added sugar, beans, lentil/whole-grain items, nuts, protein-forward options) and skip high-GI picks to avoid next-morning crashes.
Notes
PDF: https://jn.nutrition.org/article/S0022-3166%2823%2972746-6/pdf