What first comes to mind when you picture a healthy lifestyle? Many of us tend to focus on what we eat and how active we are. But an oft-neglected part of the picture is not just what we do, but when we do it. Establishing a regular sleeping and eating schedule can improve health in as little as one week. Two experts in sleep and metabolism explain why.
Keeping Time
The answer has to do with the circadian clock: an internal biological 24-hour clock that鈥檚 present throughout the human body, in every cell. 鈥淭he circadian clock machinery evolved to help your body anticipate what鈥檚 going to happen,鈥 says assistant professor in the Department of Nutrition & Integrative Physiology at the University of Utah College of Health.
Chaix researches the connection between our internal clock and metabolism, or how we take in and use energy from food. Maintaining good metabolic health reduces the risk of type 2 diabetes, heart disease, and many other serious health conditions.
A well-functioning clock helps our bodies prepare for daily life by tweaking our metabolism based on the time of day, Chaix explains.
At night, for example, the clock preemptively routes energy toward consolidating memories and detoxifying the body, which happen most while we sleep. When we wake up in the morning, the clock revs up our metabolism to prepare to eat and be active. Light exposure during the day鈥攁nd darkness at night鈥攌eep the clock running in time with the outside world.
When You Eat Matters
This means that the exact same meal can impact your body differently, depending on what time of day you eat. Shortly after waking, the body is prepared to digest food with peak efficiency, thanks to increased responsiveness to the blood sugar-lowering hormone insulin. 鈥淓ven if you have a massive amount of carbohydrates, the way your body鈥檚 going to metabolize it is very efficient because it is the right time of day to do it,鈥 Chaix says. In other words, a big breakfast won鈥檛 cause the same spike in blood sugar as the same meal eaten later in the day.
On the other hand, eating late at night can be especially unhealthy. Lots of energy is allocated to the brain and the liver at night, to maintain the body processes that happen during sleep. An unexpected midnight snack forces the body to suddenly reroute energy to the digestive system, striking an uncomfortable compromise between digestion and sleep-related processes.
The Importance of a Sleep Schedule
But lack of sleep can disrupt the clock, which in turn disrupts metabolism, warns assistant professor in the College of Health鈥檚 Department of Health & Kinesiology. When you don鈥檛 get enough sleep, you鈥檙e often also exposed to lots of electronic light late at night, which makes the clock try to reset to match the light cycle. 鈥淚t鈥檚 like you鈥檙e inducing jet lag continually,鈥 Depner says.
And that jet lag has rapid health consequences. Depner鈥檚 research has found that sleep-deprived people are more likely to eat more鈥攁nd eat late at night, which can noticeably decrease insulin sensitivity in less than a week. 鈥淲e can take people from healthy to a level of insulin sensitivity that would almost be prediabetic in as short as five days,鈥 Depner says. 鈥淚t鈥檚 really scary.鈥
It takes about a week of sufficient sleep to reverse the metabolic changes, he adds鈥攕leeping in on weekends isn鈥檛 enough.
Eating late at night can also affect the internal clock of the digestive system, potentially knocking it out of sync with the light-based clock found in the brain. Ideally, eating breakfast shortly after you wake up keeps your digestive system synchronized with your brain.
However, 鈥淚f the food comes when it鈥檚 not supposed to, then the digestive system is running on a time that鈥檚 different from the brain,鈥 Chaix says. 鈥淚t鈥檚 like having your brain in Boston and your guts in San Diego.鈥 Long-term misalignment can weaken the clock as a whole, making it harder to fall asleep and harder to wake up, Chaix says.
How to Set Your Clock
Getting enough sleep and keeping a consistent schedule are often difficult鈥攁nd sometimes impossible. But small steps can help strengthen the circadian clock and improve health even in tough circumstances.
鈥淓ven if you鈥檙e not able to get enough sleep, other strategies can help mitigate some of the health consequences,鈥 Depner says. Because bright light sets the brain鈥檚 circadian clock, starting your day with plenty of light exposure can help, Depner says, as can avoiding bright electronic light late in the evening. He鈥檚 currently testing ways to in people with chronic poor sleep.
Chaix adds that maintaining a regular schedule can be beneficial, even for people who work or are active at night. 鈥淐onsistency is the key,鈥 she says. 鈥淲hatever rhythm you have, stick to it so that your clock can adapt and predict that cycle, even if it鈥檚 not the cycle that鈥檚 completely the same as the sun.鈥 Part of aims to help figure out the healthiest times to eat for people who work night shifts.
While recalibrating one鈥檚 schedule may seem like a big task, Chaix adds, even small adjustments can help. 鈥淚t doesn鈥檛 have to be that tomorrow you wake up and you implement all of these all at once,鈥 she says. 鈥淭here are little steps, and all of them are toward a mighty goal of improving health.鈥
