Getting more sleep at night appears to help some people unconsciously cut back on the amount of sugar they eat during the day, according to a preliminary finding from a study published in the American Journal of Clinical Nutrition.
The study’s main purpose was to see if people who regularly sleep for less than the recommended seven hours could get more sleep by following a few low-cost, easy-to-implement strategies.
They could — by as much as 1 hour 17 minutes per night.
The researchers then conducted what they call “a pilot study” to determine the impact, if any, the increased shut-eye had on the participants’ eating habits.
They found that when participants got more sleep, they consumed, on average, 2.5 fewer teaspoons of sugar each day.
“‘Sleep duration and quality is an area of increasing public health concern and has been linked as a risk factor for various conditions,” said Haya Al Khatib, the study’s lead author and a doctoral student in nutrition science at King’s College London, in a released statement. “We have shown that sleep habits can be changed with relative ease in healthy adults using a personalized approach.”
“Our results suggest that increasing time in bed for an hour or so longer may lead to healthier food choices,” she added. “This further strengthens the link between short sleep and poorer quality diets that has already been observed by previous studies.”
A randomized trial
For the study, Khatib and her colleagues recruited 42 healthy adults, aged 18 to 64, who reported being “short sleepers” (people who get less than seven hours of sleep on a typical night). In addition to undergoing a series of biomedical tests, the participants were asked to wear an actigraph (a wrist-worn device that detects physical activity) for a week and to keep sleep and food diaries. (The devices confirmed that all of the participants were short sleepers.)
The participants were then randomly divided into two groups. One group met individually with a sleep psychologist, who counseled them on the importance of sleep and helped them devise a personal plan to extend the amount of time they slept each night. Participants were given lists of healthy sleep tips from such resources as Harvard University and Great Britain’s National Health Service. From those lists, they selected at least four to put into practice over the next few weeks. The tips included such standard advice as “avoid caffeine late in the day,” “establish a soothing pre-bedtime routine,” and “don’t go to bed either hungry or too full.”
The other participants (the “control” group) received no consultation. They were simply instructed to go about their regular daily (and nightly) activities.
After three more weeks, both groups were asked to wear the wrist actigraph for another seven days and nights and to fill out additional sleep and food diaries. The researchers then compared the data collected that week with the data collected at the start of the study.
Primary findings
Of the people who received a sleep consultation, 86 percent increased the average amount of time they spent in bed and 50 percent increased the amount of time they slept.
The control group, on the other hand, experienced no significant change in the amount of time they spent either in bed or asleep.
Specifically, the sleep-consultation group spent an average of 56 minutes longer in bed (from 31 minutes to 1 hour 21 minutes) and an average of 52 minutes longer sleeping (from 27 minutes to 1 hour 17 minutes).
Despite that improvement, however, only three of the 21 people in the group increased their sleep enough to meet the recommended minimum of seven hours a night.
A secondary finding
When the researchers looked at the food diaries, they found an additional interesting finding. The daily diets of the participants who extended their sleep time contained about 10 fewer grams of added sugar, on average, at the end of the study than at the beginning.
Their diets also contained fewer total carbohydrates and fats, but this result was less strong.
“The fact that extending sleep led to a reduction in intake of free sugars, by which we mean the sugars that are added to foods by manufacturers or in cooking at home as well as sugars in honey, syrups and fruit juice, suggests that a simple change in lifestyle may really help people to consume healthier diets,” said Wendy Hall, the study’s principal author and a senior lecturer at King’s College London, in the released statement.
Limitations
Although this was a randomized controlled study, it involved only a small number of people and lasted for only a few weeks. A larger, longer study would be needed to determine how much of an effect sleep education and training has on people’s sleep patterns.
That caveat is particularly true for the study’s secondary (and preliminary) finding regarding sugar consumption.
Still, the sugar finding is intriguing. Ten grams of added sugar — or 2½ teaspoons — represents about 40 calories, an amount that can quickly add up over time.
Furthermore, other research has demonstrated that depriving people of sleep increases their calorie intake. People who are short sleepers tend to both eat more frequently during the day and to consume more high-calorie snacks at night. One study found that just a short period (five nights) of severely restricted sleep (four hours) resulted in an average weight gain of about two pounds.
And we are a very sleep-deprived country. More than a third of adults in the United States say they get less than six hours of sleep on most nights.
FMI: The study can be read in full on the website of the American Journal of Clinical Nutrition. For tips on how to improve your sleep, go to the National Sleep Foundation’s website.
