The last meal of the day does more than simply end the evening — it may also affect how well we sleep and what we choose to eat the next morning. That’s the conclusion of a study led by the University of Granada and published in the 'European Journal of Nutrition'. (source in Spanish)
“The evening meal influences sleep, and sleep in turn affects breakfast habits the next day,” the researchers explain. Rather than a one-way relationship, the study points to a two-way connection in which diet and sleep continuously influence each other.
To explore this link, the researchers followed obese men and women for 14 consecutive days under real-life conditions. Participants recorded their meals, especially dinner and breakfast, while their sleep was objectively monitored using accelerometers and sleep trackers.
Unlike laboratory-based studies, this approach allowed researchers to observe everyday habits as they naturally occur. As the authors point out the goal was to better understand how food and sleep interact in daily life, where many factors come into play at the same time.
Why dinner affects sleep
One of the study’s main findings is that the nutritional composition of dinner is closely linked to sleep quality that same night. According to the researchers, meals high in calories, fat, cholesterol, protein, alcohol, red meat or fried foods were associated with poorer sleep.
By contrast, certain foods appeared to support better rest. Dinners richer in carbohydrates, olive oil and oily fish were linked to improved sleep quality. The findings suggest "the nutritional components of the evening meal may influence different sleep parameters".
That said, the researchers caution that the study was observational, meaning it cannot prove direct cause and effect.
Sleep also shapes eating habits
The relationship also works in the opposite direction: sleep quality appears to influence what people eat the following morning. The researchers found that "poorer sleep quality is associated with less healthy breakfast habits".
Specifically, the data point to several patterns:
- People who woke up later tended to consume more calories at breakfast.
- More fragmented sleep was associated with higher sugar intake and lower fibre consumption.
- Longer sleep duration was linked to healthier overall breakfast quality.
These findings reinforce the idea that sleep is not simply a result of diet, it can also shape future food choices.
A cycle that repeats every day
According to the researchers, one of the study’s most important contributions is showing how closely food and sleep are connected in everyday life. Dinner, sleep and breakfast appear to form part of the same cycle, where small changes in one area can influence the others.
While the effects observed in the study were relatively modest, the findings offer new insight into how daily habits interact. The researchers believe this could eventually help improve obesity prevention and treatment strategies by considering not only what people eat, but also when they eat and how well they sleep.
