Based on the findings, it would appear sleep and wake cycles are linked with our metabolic health. Specifically, the night owls in this study had a reduced ability to use fat for energy, which can result in fat accumulation and subsequently, increased risk for disease. They were also more likely to be insulin resistant, with insulin resistance being strongly linked to heart disease and type 2 diabetes.

The early birds, on the other hand, were found to use more fat for energy while exercising and at rest, compared to the night owls. They were also typically more active and had better fitness levels than the night owls.

As the study’s senior author Steven Malin, Ph.D., explains in a news release, “The differences in fat metabolism between early birds and night owls shows that our body’s circadian rhythm could affect how our bodies use insulin. A sensitive or impaired ability to respond to the insulin hormone has major implications for our health.”