Objective: Although intake of specific macronutrients has been associated with sleep parameters, interventional evidence is lacking. Therefore, this randomized trial was conducted to examine how a more unhealthy high-fat/high-sugar (HFHS) diet impacts sleep in humans.

Methods: In a crossover study, 15 healthy young men consumed two isocaloric diets in random order for a week: an HFHS and a low-fat/low-sugar diet. Following each diet, in-lab sleep was recorded using polysomnography during a full night of sleep and during recovery sleep after extended wakefulness. Sleep duration, macrostructure, and microstructure (oscillatory pattern and slow waves) were investigated using machine learning-based algorithms.

Results: Sleep duration did not differ across the diets based on actigraphy and the in-lab polysomnography. Sleep macrostructure was similar after 1 week on each diet. Compared with the low-fat/low-sugar diet, consumption of the HFHS diet resulted in reduced delta power, delta to beta ratio, and slow wave amplitude but increased alpha and theta power during deep sleep. During recovery sleep, similar sleep oscillatory changes were observed.

Conclusions: Short-term consumption of a more unhealthy diet alters sleep oscillatory features that regulate the restorative properties of sleep. Whether such changes can mediate adverse health outcomes associated with consumption of an unhealthier diet warrants investigation.