The relationship between sleep and diet has been explored thoroughly when it comes to sleep affecting diet choices. But what is lacking is information about how diet affect sleep. This raises the question: could following a calorie-restricted diet affect your sleep quality?
Studies have found that about 30% of American adults are chronically under-sleeping, and there are similar statistics for Australia. Adults report issues with initiating or maintaining sleep.
Short sleep, poor sleep quality and disordered sleep patterns are related to many chronic conditions including obesity and obesity-related conditions. Diet-related weight loss is considered to improve sleep quality and increase sleep duration.
Dietary protein may be one factor that influences sleep, thanks to the amino acids needed for sleep-related neurotransmitters such as melatonin and dopamine. However, there is limited evidence that suggests a higher-protein diet during weight loss improves subjective indices of sleep in overweight and obese adults.
The researchers designed a study to explore the effects of a higher-protein energy-restricted diet on sleep quality. They utilised data from a 14-week free-living study, with a 2-week baseline and 12-week randomised controlled-feeding intervention.
51 participants took part in the trial. Participants were aged 30-69 years, BMI 25-39, and weight stable (± 3kg) during the previous 3 months. They had a global sleep score of ≥5, indicating poor sleep quality.
Exclusion criteria include smoking, diabetes, acute illness, pregnancy and lactation, high blood pressure, high cholesterol and triglycerides, waist circumference of >102cm for men and >88cm for women, or a diagnosis of severe sleep apnoea or insomnia.
The participants consumed a Healthy US-Style Eating Pattern diet, and were randomised to one of two groups – recommended protein (RP) or high protein (HP) diet. Healthy US-Style Eating Pattern includes a variety of vegetables, fruits, whole grains, fat-free or low-fat dairy, seafood, poultry, meat, eggs, nuts, seeds, and soy products.
The RP group consumed 5oz of protein per day, and the HP group consumed 12.5oz of protein per day. For the HP group, the additional protein was in the form of animal-based proteins such as eggs, meat, poultry, and seafood. Each participant had a ~750kcal/day deficit. All food was provided via an online order to a local supermarket.
Objective and subjective sleep quality indices were measured at baseline, week 6 and week 12. Objective data came from wrist-worn actigraphy and subjective from Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale.
Among all participants, body mass decreased by an average of 6.2kg. Dietary protein intake did not affect any objective or subjective sleep quality outcomes measured.
Sleep efficiency improved, as did daytime sleepiness scores and global sleep scores.
Participants transitioned from being categorised as ‘poor sleep’ to ‘good sleep’, with the average global sleep score dropping from 7.6 at baseline to 4.8 at 12 weeks.
The researchers concluded that overweight or obese adults who are poor sleepers may improve their sleep while consuming either the recommended or a higher-protein energy-restricted Healthy US-Style Eating Pattern.
Several limitations were noted. Participants knew prior to enrolment that their sleep was being assessed, so they may have anticipated that their sleep would improve with time, leading to a placebo effect.
The imbalance between male and female participants could have influenced the outcome, as females tend to require more sleep, have a shorter circadian cycle, and recover quickly from sleep deprivation.
There was a higher drop-out rates in the HP group due mostly to non–study-related reasons. This data loss could explain the null results. Finally, the researchers could not be certain that only the study foods and beverages provided were consumed, as it was a free-living study.
Further studies are required to explore the impact of diet and protein intake on sleep quality.
Hudson, J.L., Zhou, J. and Campbell, W.W., 2020. Adults Who Are Overweight or Obese and Consuming an Energy-Restricted Healthy US-Style Eating Pattern at Either the Recommended or a Higher Protein Quantity Perceive a Shift from “Poor” to “Good” Sleep: A Randomized Controlled Trial. The Journal of Nutrition.