But can you avoid these risks if you are standing later?
Rather than the hour at which you fall asleep, the results of the study suggest that control of blood sugar is linked to the circadian rhythm of your body (alias your internal clock), says the main author, Daisy Duan, MD, an endocrinologist by emphasizing diabetes and obesity in Johns Hopkins Medicine in Baltimore.
“Overall, it always seems that it is better to avoid eating a late dinner, even if you do not fall asleep right after,” explains Dr. Duan.
The study examined the effects of early and late dinners
To reach this conclusion, Duan and his colleagues recruited 13 healthy adults who were 25 years old, on average, and supervised them in a sleep laboratory.
To determine the start of the “biological night” of each volunteer, the researchers measured their melatonin levels by testing their saliva. The body naturally produces this hormone inducing sleep in response at nightfall.
“The time when melatonin levels begin to increase are indicative of the beginning of your biological night,” explains Duan, qualifying this method of “gold standard” to assess the circadian rhythms of a person.
The researchers measured the levels of glucose and insulin of each participant every hour for 24 hours via IV.
Scientists have evaluated these measures in three scenarios:
- When the participants ate a dinner early (three hours before the start of their unique organic night), I will sleep five hours later
- When the participants ate a late dinner (an hour after the start of their unique organic night), I will sleep an hour later
- When the participants ate a late dinner (an hour after the start of their unique organic night), I will sleep five hours later
The volunteers were able to sleep eight full hours in the three scenarios, and they seemed to have the same quality of sleep, whatever the circumstance. For dinner, they all obtained the same meals, with total calories depending on the weight of each person.
The researchers compared blood sugar four hours after the dinner of each of the three scenarios. They found that the two late delay scenarios caused glucose levels which were 11% higher, on average, than the scenario of the start of dinner. Delaying sleep had no impact.
The study has certain limits
Duan and his team emphasize that these results of the study are preliminary. They have not yet completed a complete data analysis or submitted the results to a medical newspaper for peer exams and potential publication.
Ajaykumar Rao, MD, an endocrinologist of diabetes and metabolism with Temple Health in Philadelphia, which was not involved in research, draws attention to several limits of the analysis. It was produced with a very small group of only 13 adults, in a very controlled environment which did not reflect real behavior. In addition, the study was very short, so it may not reflect the long -term effects of late food or late sleep.
Because the study included only young healthy adults, it considers results as more applicable to the prevention of diabetes rather than suggesting lifestyle changes for people who are already suffering from diabetes.
“The results suggest that the cumulative effects of late consumption put people at risk to possibly develop resistance to insulin, which is a precursor of diabetes,” said Dr. Rao.
“When you eat later, your body’s response to a glucose load can be a little attenuated because your own insulin levels do not attack this meal in the same way as they would do it,” he said.
The natural rhythms of your body should determine when you eat and sleep
For Theresa Gentile, RDN, spokesperson for the Academy of Nutrition and Dietetics, the study highlights the importance of being in line with your own circadian clock.
“You should try to pay attention to the natural rhythms of your body by noting when you start to feel sleepy in the evening,” said Gentile, who was not involved in research. “Obtise to finish dinner at least a few hours before this time.”
She suggests two ways to better understand your circadian rhythms. “A recorded dietitian-nutritionist can help you follow your typical sleep and hunger models,” she said. “Or you can use tools such as laptop sleep trackers to help identify the start of your personal organic night, so you can time meals and sleep for optimal health.”
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