Social jet lag may be harmful in the same way, says David J.

CNN: Is 'social jet lag' harming your health?

"With social jet lag, we're forced to eat at times when the body doesn't want to eat, or isn't prepared for digesting food properly, " he says.

CNN: Is 'social jet lag' harming your health?

Most people experience at least some social jet lag.

CNN: Is 'social jet lag' harming your health?

Study researcher Renee Biss, a graduate student at the University of Toronto, said one of the reasons morning people may be happier is because they tend not to suffer from social jet lag.

CNN: STORY HIGHLIGHTS

TIME.com: Is social jet lag making you fat?

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Some of the proposed explanations for the link between shift work and obesity, such as irregular meal times and metabolism disruptions at the cellular level, may help explain the social jet lag findings as well, Roenneberg says.

CNN: Is 'social jet lag' harming your health?