One method of creating a nutritional framework is to think about three different forms of dietary restriction:
- The foods you eat or don’t eat - dietary restriction
- How much you eat - caloric restriction
- When you eat - time restriction
Of these three forms, time restriction may be the easiest to change and quite beneficial for sleep.
In his book The Circadian Code, Satchin Panda recommends time-restricted eating (TRE). Time-restricted eating refers to the practice of consuming all calories within a specific window of time throughout the day. Many people consume calories within an hour of waking up and throughout the day up until bedtime. This could amount to an eating cycle of 15 hours or more. The human body has not evolved to process and digest food during such a large portion of the day. The goal is to shorten this timeframe to create a smaller window when you eat.
Why is it good to eat within a specific time window?
Based on some human and animal studies, it appears that a shortened feeding period provides the digestive system the right amount of time to perform its function uninterrupted by a new influx of food. A shorter eating window also provides enough time for the body to repair and rejuvenate and supports healthy gut bacteria.
Most of the body’s fat-burning happens 6 to 8 hours after finishing your last meal. If you reach at least 12 hours of fasting, the results are even better. It is believed that the optimum eating window is between 8 and 11 hours. Studies have shown health benefits increase as the eating window decreases starting at 12 hours down to about 8 hours where things level off. For example, some people follow a 16-8 time restriction, which means 16 hours of fasting and 8 hours of eating in a single day.
Action: Start with establishing a 12-hour eating window. For example, if you finish dinner by 7 PM, you would not consume any calories until 7 AM. Try gradually decreasing the eating window if possible. You can either eat dinner an hour earlier or eat breakfast (or have that coffee) an hour later. Even small changes can have positive health benefits.
What does this have to do with sleep?
Melatonin is a hormone that is released by the pineal gland in the back of your brain that regulates the timing of when sleep occurs. Melatonin production is usually triggered soon after dusk, and levels begin to rise 2 to 4 hours before your typical sleep time. The release of melatonin is a signal to all systems in the body to prepare for sleep. This includes metabolism as well as organs like the pancreas that produces insulin.
If melatonin is rising and you eat, the food triggers the insulin response to begin. Insulin helps your liver and muscles absorb glucose from your blood so that your blood glucose doesn’t rise too high. Since it is later in the evening, the insulin response is slowed which may allow the blood glucose levels to remain high for a longer period of time. A consistent pattern of high blood glucose leads to pre-diabetes and type 2 diabetes. In addition, the body might store the excess glucose in the blood as fat instead of using it as fuel.
Eating close to bedtime may cause other issues. Digestion slows down as bedtime nears, and this means it takes longer to process food. This could lead to acid reflux or stomach cramps.
Eating late is like arriving at a restaurant 15 minutes before closing time. The kitchen is cleaned up and everything is put away, and yet you barged in demanding a meal. Fortunately, the restaurant manager can save you from yourself until you find the closest fast food joint open late. At that point, your digestive system is forced to process Taco Bell’s fabled “Fourth Meal.”
Action: Have your last meal at least 3 to 4 hours prior to bedtime and avoid snacking at night. If you are going to have a cocktail, beer, or glass of wine, have it either before dinner or accompanying your meal.
A small change to when you eat, regardless of changing what you eat or how much you eat, can have many benefits for sleep and overall health.