The early bird gets the worm, the night owl gets sick: establishing the chronic health effects of individuals with an evening preference

By Mohamad Hamze

The first ever review of studies focusing on sleeping habits has reported on what we’ve all known to be true but have collectively accepted as part of college, work, and social life: late nights have the potential to be detrimental to our long-term health. A research team from Northumbria University in Newcastle, UK has analyzed a number of studies that focus on the effects of evening preference on metabolism and cardiovascular health.

A person’s long-term sleep and wake habits can influence their circadian rhythm, or chronotype, and lead to a preference towards morning or evening. These studies correlated evening chronotypes with various dietary trends that can be associated in chronic ill-health effects such as heart disease and type 2 diabetes, including the tendency to eat fewer and less-structured but heavier and less-healthy meals than those with morning chronotypes. A member of the research team, Dr. Leonidas G Karagounis of Nestle Health Science in Switzerland, elaborates that the poorer diet of evening chronotypes consists primarily of a “lower intake of fruits and vegetables, and higher intake of energy drinks, alcoholic, sugary and caffeinated beverages, as well as higher energy intake from fat.” Eating late at night also seems to exacerbate the effect of one’s shifting internal clock, causing a spike in glucose levels that the body expects to be lowest before bed. This deviation from the body’s normal metabolic processes “reduces their sensitivity to insulin and affects their glucose tolerance, putting them at greater risk of developing type 2 diabetes,” according to the article.

Poor eating and sleeping habits in adulthood are established in childhood and adolescence, but while there do exist many possible influential genotypic, societal, and geographic factors that have been implicated in an individual’s chronotype, more research is needed to understand how these factors manifest in the physiological differences between early risers and late-nighters.