A scientific recipe that helps babies stop crying, calm down and sleep in bed

New research published in Current Biology on September 13 demonstrates the importance of carrying crying infants rather than simply holding them. Led by Kumi Kuroda at the RIKEN Center for Brain Science (CBS) in Japan, the study details how crying babies are physiologically affected by being held, carried, and laid down. The data yield a simple but cost-free and effective technique that increases the chance of getting a crying infant to calm down and sleep in bed.

Most parents know the occasional frustration and discomfort of dealing with a crying baby. For some, it’s a regular occurrence that affects the baby’s ability to sleep and stresses out the parents. What can you do in this situation? Kuroda and her team found a “Transport Response” in distressed mouse pups and human babies in which infants calm down when carried by their mothers. The response is a complex series of parallel biological processes that result in reduced crying and lower heart rates, which helps parents to transport the infants.

baby crying

Based on the ‘Transport response’ in which distressed animals calm down when carried, the behavioral and physiological data in this study showed that when babies are crying a lot, walking for about 5 minutes, following by sitting for about 8 minutes should help calm them down and put them to sleep. Note, sitting and holding a crying baby never calmed them down and heart rates rose. Putting babies to sleep immediately after walking often led to higher heart rates and woke babies up./photo:RIKEN

 

The new study used a baby ECG machine and video cameras to systematically compare changes in heart-rate and behavior as mothers acted out activities that are commonly used to calm infants, including carrying, being pushed in a stroller, and holding while sitting. Data during these activities were recorded from babies that were crying, awake and calm, or sleeping. At each heartbeat, behavior was assessed as asleep, alert, or crying, and scored accordingly. This way the researchers could track changes in both behavior and physiology with sub-second precision.

The experiment led to a few important findings. First, as Kuroda explains, “walking for five minutes promoted sleep, but only for crying infants. Surprisingly, this effect was absent when babies were already calm beforehand.” Among the babies studied, all had stopped crying by the end of the five-minute walk and had reduced heart rates, and about half were asleep. Second, sitting and holding crying babies was not calming; heart rates tended to go up and crying persisted.

The heartbeat measure allowed the researchers to dissect the effect of each micro-activity as infants were handled. The researchers found that the babies were extremely sensitive to all movements by their mothers. For example, heartrates went up when mothers turned or when they stopped walking. The most significant event that disturbed the sleeping infants happened just when they became separated from their mothers.

infant-small child

Every mother has experienced the disappointment of having a finally sleeping baby wake up again after being put down. The researchers pinpointed the problem using the heartbeat data. “Although we did not predict it,” says Kuroda, “the key parameter for successful laydown of sleeping infants was the latency from sleep onset.” Babies often woke up if they were put down before they got about 8 minutes of sleep. Thus, based on the data, Kuroda recommends that when babies are crying too much and can’t sleep, mothers should carry them steadily for about 5 minutes with few abrupt movements, followed by about 8 minutes of sitting before laying them down for sleep.

Although this procedure does not address why some babies cry excessively and cannot sleep, it offers an immediate solution that can help parents of newborns. Additionally, the researchers recognize the usefulness of heartrate data in this age of wearable fitness devices. “We are developing a “baby-tech” wearable device with which parents can see the physiological states of their babies on their smartphoness in real-time,” says Kuroda. “Like science-based fitness training, we can do science-based parenting with these advances, and hopefully help babies to sleep and reduce parental stress caused by excessive infant crying.”

Heart patients advised to move more to avoid strokes

Elevated blood pressure, high cholesterol and diabetes increase the risk of heart disease. But a large study today reveals that in people with these conditions, increasing activity levels is associated with a reduced likelihood of heart events and mortality. The research is presented at ESC Preventive Cardiology 2021, an online scientific congress of the European Society of Cardiology (ESC).1

Study author Dr. Esmée Bakker of Radboud University Medical Center, Nijmegen, the Netherlands said: “Previous research showed that improvements in physical activity are beneficial to health. However, those studies were performed in the general population. In our study, we were interested to see if there were similar effects in individuals with cardiovascular risk factors such as high blood pressure, high cholesterol, and diabetes.”

The study included 88,320 individuals from the LifeLines Cohort Study. Participants underwent a physical examination and completed questionnaires about their medical history and lifestyle including exercise. The questionnaires were repeated after approximately four years.

Study participants were divided into five groups according to activity levels at baseline and four years: large reduction, moderate reduction, no change, moderate improvement, and large improvement.2 Participants were followed-up for a median of seven years after the first assessment for the occurrence of cardiovascular disease or death.

Hyper tension

A total of 18,502 (21%) individuals had high blood pressure, high cholesterol, and/or diabetes at the start of the study. The average age of this group was 55 years. After adjusting for age, sex, and baseline physical activity, the researchers found that those with a moderate to large improvement in physical activity were around 30% less likely to develop cardiovascular disease or die during follow-up compared to those who did not change their activity level.

The remaining 69,808 (79%) participants did not have high blood pressure, high cholesterol, or diabetes at the start of the study. The average age of this group was 43 years. After adjusting for age, sex, and baseline physical activity, the researchers found that those with large reductions in physical activity had a 40% higher risk of cardiovascular disease or death compared to those who did not change their activity level.

Dr. Bakker said: “Our study suggests that to prevent heart attacks and strokes and boost longevity, healthy individuals should maintain their physical activity levels, while those with risk factors need to become more active. The associations we found were even more pronounced in people who were relatively sedentary at the start of the study, indicating that inactive people have the most to gain.”

To prevent heart disease, European guidelines recommend at least 150 minutes a week of moderate intensity or 75 minutes a week of vigorous intensity aerobic physical activity or an equivalent combination.3

Dr. Bakker said: “If you are currently sedentary, walking is a good activity to start with. If you are already hitting the recommended amount, try doing 10 minutes more each day or increasing the intensity.”