Well+Good: It’s not just what you eat that affects sleep, when you eat matters, too.
According to scientific research, mealtimes directly affect the body’s circadian rhythm, aka the natural physical, mental, and behavioral changes that follow a 24-hour cycle.
This connection affects health in both short- and long-term ways. Here, three experts explain the connection between mealtime and sleep, breaking down why exactly it’s so important. Plus, they give tips on how to use it to your advantage—even when you’re traveling or if you work the night shift.
Before we get into the connection between mealtime and sleep, it’s helpful to know why exactly circadian rhythm is important in the first place. “Our circadian rhythm is the 24 hour rhythm of activity which is hard-wired into every cell in the body. This helps all our internal systems—such as appetite, metabolism, cardiovascular system, body temperature, and immune function—run in sync with each other,” says Sophie Bostock, PhD, also widely known as The Sleep Scientist. “It enables the right things to get to the right places at the right time.”
Dr. Bostock explains that the brain relies on signals from the outside world to keep the body clock in sync with the environment, which is how it operates best. “The strongest signal is light, which helps to drive activity and alertness via a master clock in the brain,” she says. This is why the majority of society is set up to, for the most part, function during daylight hours and sleep at night.
When we eat, she adds, also affects circadian rhythm. “[Eating] signals to the clocks in the liver, heart, muscles, and kidneys that it’s time to get to work,” she says. In other words, consuming food alerts the body that it’s time to work, not rest. So eating close to when you plan to go to sleep signals to the body that it actually shouldn’t be winding down; it needs to stay up to process the meal.