Sleep is increasingly being recognized as vital to good health. Not only does it help us feel good and function effectively, it is necessary for good physical health. While many people are concerned about getting poor sleep, even more are concerned about their excess weight. As I have previously discussed, sleep and weight gain or loss are related in important ways. Sleep problems such as sleep apnea have been associated with weight gain and ultimately with type II diabetes, a major health concern in the modern world. The connections between sleep, food and weight are complex and involve the impact of food on sleep and alertness; the effect of adequate sleep or sleep loss on metabolism, appetite and weight gain/loss; and the possible underlying psychological and physiological reasons for these connections.
One aspect of the relationship between food and sleep involves the amino acid tryptophan. Some foods such as turkey and bananas are rich in tryptophan. It was long believed that heavy consumption of foods with large amounts of tryptophan in them caused the frequently experienced post–Thanksgiving- feast stupor. More recently it is though that general overindulgence in foods containing a lot of fat and carbohydrate may be the main reason for this unpleasant after effect of a very large meal. It is also true that there is a natural low in the middle of the afternoon, sometime around 2:00 PM, and this is often what people mistakenly believe is the result of a big lunch rather than a normal low in the circadian rhythm. Although it is vital substrate for the neurotransmitters serotonin and melatonin, tryptophan does not easily cross the blood brain barrier that protects the brain from harmful chemicals and infectious agents in the blood stream. Carbohydrates do aid in the transport of tryptophan across this barrier and into the brain where it can be synthesized into neurotransmitters. So a light snack with some carbohydrate and protein such as cereal and milk, peanut butter and toast, cheese and crackers, a half bagel, a handful of oyster crackers with a fruit or 2 cups of air popped popcorn works well for some people to create a mild sense of drowsiness when consumed 45 minutes to an hour before bedtime. The before bedtime snack should be light, perhaps 100 to 150 calories, and most likely should not be used by people with diabetes who must carefully control their sugar levels. A cup of chamomile tea or warm milk may also be a good bedtime snack.
On the other side of the night, in the morning, foods that increase alertness are things that help wake up our senses like spicy V8 juice (the spice helps increase metabolism and the shock to the taste buds helps wake us up). Other foods that people have used to help jolt them awake include the curiously strong Altoids mints and those Listerine strips that help wake up your mouth. The old standby coffee also works well because of the stimulant caffeine. It has been found that small doses of caffeine over time (such as a cup of tea every few hours) tend to maintain alertness better than a single large blast of caffeine in the morning that will eventually wear off and may leave you feeling more tired and sleepy later. It is best not to use caffeine too late in the day, say after 2:00 PM, as it can stay in the system for many hours and may later interfere with sleep. While residual caffeine in the body may not keep us from falling asleep it can contribute to disrupted and fragmented sleep later in the night. Energy drinks are very popular but not recommended from a sleep point of view. The primary ingredient in them is caffeine but often with a lot of vitamins, supplements and sugar you probably don’t need and that can lead to a “crash” type effect as the drink wears off.
A word is in order about alcohol. While many people do use alcohol as a sleep aid, current research shows that it is not recommended and is most likely counterproductive. Alcohol does indeed have an initial effect of relaxing us and may encourage sleep. Initially it may even deepen sleep but later, as it is metabolized out of the body, a rebound occurs and sleep is likely to be more fragmented and of poorer quality later in the night.
It has been observed that adults who sleep less than 5 or 6 hours a night are at increased risk for weight gain. A recent study by researchers at the University of Colorado may help explain this observation and also shows the complexity of the relationship between sleep and weight gain. The study involved 16 volunteers who were followed over two weeks in a controlled environment where their food intake and energy utilization could be precisely monitored. After a baseline period the participants were split into 2 groups with one group spending five days getting only five hours of time to sleep per night and the other getting nine hours of time to sleep. After this, the groups switched places for the next five days. The sleep deprived participants gained an average of several pounds over the course of the study. Interestingly, those in the five-hour condition used more energy during waking hours but more than made up for this by eating more. The participants that were sleep deprived often ate less for breakfast but snacked heavily after dinner. The researchers speculate that there are circadian effects in this pattern. Breakfast eating was decreased as the participants were up several hours before their biological night was over and they were not ready to consume. Eating heavily in the evening meant eating at a time when the body is not prepared for the intake of food.
Recent research has show that the hormones leptin, ghrelin and cortisol are extremely important with regard to weight gain and loss. Their effects are complex and not fully understood. Ghrelin is released by the stomach and has a number of effects including increasing feelings of hunger and slowing metabolism. After a significant weight loss there is often an increase in the production of ghrelin. It seems that the body may be trying to regain the lost weight by increasing hunger and decreasing the use of energy by the body. One of the benefits of bariatric surgery (such as gastric bypass) for extremely obese individuals is that the production of ghrelin is decreased and contributes to decreased appetite after the surgery. Leptin, on the other hand, is released by the fat cells in adipose tissue and signals the brain that sufficient calories have been consumed and appetite is reduced and energy use by the body is increased. This hormone helps produce the feeling of satisfaction we experience after a meal. After weight loss, leptin levels tend to be decreased and this may result in increased appetite which may make it difficult to maintain the weight loss. Finally cortisol is a hormone that is released by the adrenal glands and is important in the stress response and in the regulation of the immune system. When we are under prolonged stress, cortisol levels are elevated and this may influence the distribution of fat accumulation in the body with a tendency to concentrate the increased fat in the abdomen. Disruption of sleep by nighttime problems such as sleep apnea and insomnia likely disrupt the balance of these hormones and contribute to weight gain during periods of sleep loss. It may be that the body is trying to correct for the feeling of fatigue and low mood caused by poor sleep by increasing appetite in an effort to keep functioning levels up. Getting better sleep may help correct this imbalance and contribute to decreased appetite, more efficient energy utilization, and even weight loss, all other things being equal.
So the interactions between sleep, eating, weight and health are complex and as yet not fully understood. What is clear is that getting enough sleep is a vital component of good health.