What We Eat & How We Sleep

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In the last 30 years there has been great interest in understanding what sleep is, what it does and how it relates to our health. During this time there has also has been an increased effort in understanding the real meaning of the adage “you are what you eat”. Consequently, it has only been natural to see efforts trying to uncover the relationship between nutrition and sleep. As much as these efforts are laudable it is important to realize that our knowledge in these areas remains very insufficient, often leading to tantalizing yet unconfirmed ideas. However, despite these concerns, there is some reasonable and useful information available to better understand the relationship between sleep and nutrition.

Nutrition and Sleeping Disorders

One of the most common sleep disorders is sleep apnea, defined by repetitive episodes of decreased airflow while sleeping, either because of collapse of the upper airway or lack of respiratory effort. Patients with sleep apnea will have fragmented sleep and will often complain of unrestful sleep and sleepiness during the day. In addition, patients with sleep apnea may have an increase risk for cardiovascular diseases and mortality.

However, it is also being uncovered that patients who are sleepy, or who have insufficient sleep, may have a propensity to increase caloric intake, and/or alter the timing of eating. Both of these factors increase the risk for the development of obesity. This may result in a downhill spiral that continually promotes the development of both sleep apnea and obesity.

When We Eat

It has been recognized for some time that we have an internal biological clock that that has a natural circadian rhythm. The rhythm affects when we sleep and when we awaken. However, the rhythm also affects when certain hormones are released in our system, our alertness level, and possibly our ability to process what we eat. In a study in mice, feeding them during their normal sleep time led to an increase in weight compared to the group with the same caloric intake but eating during normal waking hours.

The timing of eating and the ingestion of certain foods can clearly affect our sleep.Eating or over-eating close to bedtime may cause significant heartburn, which can lead to very fragmented sleep. Caffeine can make it difficult to initiate and maintain sleep. This effect is highly variable among patients. Some patients will deny that caffeine has any effect on their sleep, while there are other patients that must stop their caffeine intake 8 hours or more before their bedtime to prevent disturbed sleep. It is important to remember that caffeine is in a lot of foods besides coffee. Colas, energy drinks, tea, and chocolate all contain caffeine. Alcohol can also have marked affects on sleep. Interestingly, patients will often drink alcohol to help induce sleep. But this can lead to a decrease in REM sleep and increased disruptive sleep, often leading one to increase alcohol intake further.

What We Eat

There have been intriguing studies that have looked at a wide variety of nutrients and their effects on sleep. These include salt, carbohydrates, cholesterol, water, calcium, vitamin D, E, B11, B12, selenium, and other trace elements. Results range from disrupting sleep to improving sleep depending on levels and dosages. Though it is too early to have any certainty to the actual affects, it does suggest that the interaction between our nutrition and sleep may be very complex. One interesting point to note is that a decrease in iron may result in the complaint of restless legs. Restless legs is a syndrome characterized by the overwhelming need to move ones legs. In the most severe cases there is an inability to sit comfortably for any time and it may result in severe sleep disruption. Patients with this syndrome may have low iron stores from either inadequate intake or loss of iron. In this case they can be cured of their restless legs with adequate iron replacement.