Circadian misalignment and adverse cardiometabolic consequences in humans
Summary
This controlled laboratory study tested how circadian misalignment—when eating and sleeping occur about 12 hours out of sync with the body’s internal clock—affects health. Ten healthy adults followed a shifted schedule for 10 days while total sleep time was maintained. Misalignment lowered leptin, raised glucose and insulin levels, increased blood pressure, reversed the normal daily cortisol rhythm, and reduced sleep efficiency. In some participants, post-meal blood sugar reached levels typical of prediabetes. These changes occurred even though total sleep was not reduced.
Why It Matters For Night Shift Workers and Night Owls
This study shows that being out of sync with your body clock can directly harm metabolism, hormones, and cardiovascular function—even if you get enough sleep overall. For night workers, this helps explain why risks for diabetes, weight gain, and high blood pressure rise with long-term shift schedules. It highlights that when you sleep and eat is as important as how much you sleep. For workers, that means paying attention to blood sugar, blood pressure, and recovery sleep. For workplaces and clinicians, it reinforces that circadian timing itself is a key factor in protecting long-term health.
Notes
PNAS study in controlled lab conditions.