The aim of this study was to examine the effect of the day-night cycle on the transition time to full enteral nutrition in premature infants receiving oropharyngeal colostrum. The study was conducted with a randomized controlled experimental design to test the potential of an environment that supports the biological rhythms of premature infants to improve feeding processes.

The study was conducted on 60 premature infants born at 28-32 weeks of gestation. Infants were randomly assigned to experimental and control groups, and dark-colored covers were used to create a day-night cycle in the experimental group.

This study was conducted to determine the effect of day-night cycle on the transition of premature newborns receiving oropharyngeal colostrum to full enteral nutrition. The data of the study, which was conducted in a randomized controlled experimental research design between May and December 2022, were collected in the Neonatology Clinic of a university-affiliated training and research hospital in Istanbul after ethical permissions were obtained. The Neonatology Clinic is a level three Neonatal Intensive Care Unit (NICU) and has the capacity to provide specialized care for premature infants.

Sample selection was done using the randomization software at https://www.randomizer.org. As a result of randomization, 30 babies were included in the experimental group and 30 babies were included in the control group. The sample size was calculated using the G*Power 3.1 program, taking into account the findings of similar studies. As a result of this calculation, at least 28 infants were needed for each group and 30 infants were included in both groups, taking into account case losses. Data were obtained from 60 premature newborns who were hospitalized in the Neonatal Intensive Care Unit at 28-32 weeks of gestation and met the inclusion criteria.

The dependent variables of the study were: time to complete enteral nutrition, physiologic parameters (heart rate, oxygen saturation, respiratory rate), discharge time and discharge weight. The independent variable of the study is the day-night cycle established in the Neonatal Intensive Care Unit.

Inclusion Criteria:

Those born between 28-32 weeks of gestation. Infants of parents who agreed to participate in the study. Major congenital anomaly, severe systemic disease, presence of necrotizing enterocolitis, presence of suspected or confirmed sepsis, birth asphyxia (newborns with cord pH/29 arterial pH <7.0).

Newborns admitted to the NICU at ≤ 24 hours of age.

Exclusion Criteria:

Infants excluded from the inclusion criteria for this study Data Collection Forms In the data collection process, Patient Information Form including demographic and clinical information of premature newborns and Patient Monitoring Charts were used to monitor physiologic parameters during the study. In addition, a Voluntary Consent Form was used to obtain written consent from the parents.

Data Collection Tools

The devices used in the study are as follows:

Philips Intellivue MP50 Bedside Monitor: This device was used to measure heart rate, oxygen saturation and respiratory rate of premature infants.

DragerGiraffe Incubator: These are double-walled, digital weighing incubators used to monitor babies in the NICU. These incubators provide a stable environment by preventing the baby from losing heat.

Smart Sensor AS803 DigitalLuxMeter: It was used to measure the light level in the incubator head. Light level control for the babies in the experimental group was provided with this device.

Incubator Covers: Dark colored (navy blue) covers were used in the experimental group to support the day-night cycle. In the control group, standard white covers were used.

Data Collection The families of the premature infants to be included in the study were informed about the purpose, content and method of the study and their written informed consent was obtained. Newborns in both groups were administered 0.1 ml colostrum into the right and left buccal oral cavity at 3-hour intervals for 14 days. In the experimental group, a 12-hour day-night cycle was established with a white incubator cover during the day and a dark colored incubator cover at night. Physiologic parameters of the infants were recorded with monitors before and after the application. In the experimental group, a day-night cycle was achieved by using dark colored covers for the night, while standard white covers were used in the control group.

Inclusion Criteria:

• Those born between 28-32 weeks of gestation.
• Infants of parents who agreed to participate in the study.
• Major congenital anomaly, severe systemic disease, necrotizing enterocolitis presence, presence of suspected or confirmed sepsis, birth asphyxia (cord pH / 29 Newborns without arterial pH <7.0).
• Neonates admitted to the NICU at ≤ 24 hours of age.

Exclusion Criteria:

• babies excluded from the inclusion criteria for this study