If You Need to Pull an All-Nighter, This Should Be Your Diet

Diet plays an important role in helping the brain transition into a healthy sleep pattern. For example, eating something sweet can induce drowsiness. Elevated blood sugar levels increase the activity of neurons that promote sleep. One recent study showed that sleep onset latency — the time it takes to fall asleep — was significantly reduced after the consumption of high-glycemic-index food (simple sugars, bagels, donuts, and French fries) four hours before bedtime. This is related to your brain’s significant requirement for sugar in order to maintain normal function, including sleep-related functions, and the tendency for glucose to increase the uptake of tryptophan into the brain. The uptake of additional tryptophan into the brain may lead to increased production of the neurotransmitter serotonin. Increased activity of serotonin neurons is necessary for the transition from wakefulness to slow-wave sleep.

However, what if you do not wish to go to sleep, but still need to function at your best the next day?

Sleep deprivation can impair cognitive function and increase the risk of accidents and, in extreme circumstances, loss of life. While increased carbohydrate metabolism increases with normal sleep activity, it declines during sleep deprivation. The decline in carbohydrate metabolism coincides with reduced cognitive performance. The brain’s vulnerability to modifications in glucose metabolism is entirely related to the fact that glucose is the brain’s primary energy source. The brain cannot directly utilize fats or proteins for energy.

However, there is an alternative source of energetic substrates called ketone bodies. Ketone bodies are produced by the liver. There are three different ketone bodies that are always present in the blood: acetoacetate, 3-beta-hydroxybutyrate, and acetone. [Yes, your body makes acetone, a paint remover, from fat. Fortunately, the levels tend to be very low unless you are fasting.] Diets that are very low in carbohydrates, such as the ketogenic diet, will increase ketone bodies in the blood, particularly hydroxybutyrate. Neurons prefer to consume glucose and require some assistance from other molecules in order to utilize ketone bodies. In spite of the disadvantages of ketone bodies over glucose, consuming a low-carbohydrate diet does not impair cognitive function.

A recent study investigated whether a two-week low carbohydrate diet, as compared to a standard carbohydrate diet, could mitigate the negative effects of 36 hours of sleep deprivation on cognitive performance, mood, and sleepiness. As expected, the low-carbohydrate diet lowered blood glucose concentration and elevated levels of ketone bodies. Subsequently, the metabolism of ketone bodies by the brain increased about five-fold to compensate for the loss of energy typically provided by glucose.

The results showed that increased blood levels of ketone bodies may provide a metabolic benefit to the brain during sleep deprivation. In contrast, eating a high-carbohydrate diet was associated with a greater degree of irresistible sleepiness during periods of sleep deprivation. Therefore, if you need to avoid the negative effects of sleep deprivation on cognitive performance, mood and general sleepiness, it is advantageous to consume a low-carbohydrate, high-fat diet during the day.