Premature Infant Development and Sensory Environments

Noise, light, and touch may all negatively impact babies in the neonatal intensive care unit

The neonatal intensive care unit (NICU) is a very special place in hospitals where staff members have become adept at keeping even the most fragile preterm infant alive. The complexities of noise, dry-cool air, start lighting, and life-saving machinery within the NICU greatly differ from the natural, in-utero environment where the fetus is surrounded and supported by the warm amniotic fluid and protected by stable uterine walls, but the NICU does provide what the infant needs to stay alive until they have developed to a level of maturity and medical stability that allows them to thrive outside of the hospital. Some interventions include continuous supplemental heat sources, intravenous (IV) fluids, medications, invasive and noninvasive respiratory support, and more.

While these medical interventions keep fragile babies alive, research has shown that they can potentially result in negative consequences medically, psychologically, and even behaviorally for these children throughout their lives. Babies who spent time in the NICU are at an increased risk for attention deficit disorder, behavior problems and learning difficulties, which may affect their time in school and eventually their job..

Negative consequences appear to be closely associated to the day-to-day stresses preterm babies are subjected to while in the NICU, including excessive noise, bright lights, cold and heat stress, and frequent manipulation and procedures. In effort to remedy this, there must be an increased focus on providing more comprehensive and humanized care that places priority on the preterm infant’s current and future health as well as their family.

Sound is one of the most pervasive stimuli in the NICU and is perceived differently through air compared to the tissues of the womb. For the preterm infant, this is a time when auditory development is taking place, and sleep can be affected by constant startles. Noise may also cause physiological stress on infants, which can increase their length of stay or impact cognitive development.

The American Academy of Pediatrics recommends that the maximum noise level not exceed 45dB, but several studies performed in NICUs worldwide have consistently noted that the recommended noise levels have been violated-hourly levels range from 53.9 dB to 60 dB day and night. Nurses often explain that increased sound is likely largely due to monitors, procedures, presence of family, physician-nurse reports or even phones, but bed type and respiratory support systems are among the largest contributors of noise pollution in the NICU.1 New research has indicated that much of the noise in the NICU comes from the building itself and can be greater than 40dB. So, what can be done to keep noise levels down?

NICUs that have been built recently reap the benefits of improved sound insulation and design. Monitor alarms can now easily be transmitted visually or wirelessly. Intercoms can be replaced by wireless phones, and shift change discussions can and should be moved away from the bedside. Necessary mobile devices such as portable x-ray machines should be routed around to avoid the baby’s bedside as much as possible.

One study observed the effects of implementing quiet periods in the NICU (reduced light, noise, staff activity and infant handling). Findings revealed some improvement in physiologic parameters, but there was a significant difference in infant movement: only ~15 movements per hour were recorded versus 84 movements per hour without a quiet period.2

Staff members can do a lot to change the environment for their patients. For instance, they can keep necessary conversations at a very low level, discourage loud noises, such as laughing, and be careful not to place equipment (even small pieces like pens) on top of the isolettes. They should be very gentle when opening and closing portholes in the isolette and institute routine quiet periods.

Additionally, manufacturers of NICU equipment should be strongly encouraged to make every effort to reduce the noise levels of their products. Newer isolettes are designed to buffer external noise and operate more effectively to reduce the noise trauma.


Little is known about the effects of light on small infants; however, there are studies that have shown damage to the structure and function of the retina in animals. A randomized study conducted by Raman, et al., demonstrated that sick and vulnerable infants exposed to normal light levels in the NICU may develop retinopathy of prematurity.3

Additionally, continuous high intensity light exposure, the lack of systematic and rhythmic diurnal dampening of light was noted to be a concern for normal development of premature infants even in early studies.4 Very-low birth weight (VLBW) infants may be even more vulnerable to the effects of improper lighting. For instance, infants’ eyes may not be completely closed, which may increase pupil size due to decreased reactivity to light. If light intensity reaches peak levels, it can even suppress melatonin.5

When placed in nurseries with dimmed lights, premature infants progress more quickly in their sleep-wake patterns, and have improved sleep as well as diurnal variations in hormone and temperature levels.6

Enough of the currently available literature about the biological effects of light in the NICU environment should prompt healthcare providers to make a change. Nurses are the ideal group to implement change because they play a large part in making suitable accommodations for premature infants, such as covering isolettes with blankets and protecting a baby’s eyes with shades during phototherapy. Nurses should also consider dimming lights during quiet time at night when simultaneously following the noise reduction protocol.

Manipulations and Procedures
Premature infants receive a lot of hands-on attention while staying in the NICU, but how much is too much for these tiny babies?

A study, using 24-hour camera surveillance of infants in a university hospital NICU in Brazil, revealed that the infants underwent an excessive number of manipulations during 24 hours. Although many lasted less than a minute, manipulations could be as frequent as one every 10-12 minutes, resulting in an average of 2 hours and 26 minutes of manipulations over a 24-hour. This is especially staggering considering the immature infant is extremely limited in its ability to adapt to both stress and stimulation of the extrauterine environment.7

There are many opportunities to decrease interventions and because clinical nurses are probably the strongest patient and family advocates, they’re the ideal members of the team to orchestrate the change. There are numerous examples of children having better outcomes when suctioning schedules are removed and handling is decreased to the absolute minimum. Not only do the infants do better in the short-term, with more autonomic stability such as less apneas, and bradycardias, but studies have documented a decrease in the number of intraventricular hemorrhages (IVHs).9

Heat and Cold Stress
When stressed, the neonate responds by increasing energy expenditure, often at the expense of oxygenation. Whenever possible, nurses should be attempting to support the infant with thermo-neutral protection during emergency resuscitations when other staff members are attending to other life-saving interventions. Not only does hypothermia affect energy expenditure, but it affects the integrity of surfactant and in the longer-term weight gain.

When mom or dad practices skin-to-skin (kangaroo care) with their baby, nurses need to make sure that the infant is able to maintain his/her temperature. If the infant’s temperature drops, despite being wrapped in blankets and wearing a cap, he/she needs to be placed back in the isolette. It’s hard to have to take the baby away from the parents, but nurses need to implement best-practice standards that focus on the health and well-being of these vulnerable infants.

Be the Change a Preemie Needs
These are some of the potential NICU environmental issues that nurses may face change themselves. As patient advocates, nurses must take charge to ensure the environment is perfect for the vulnerable premature infants who rely on them for survival.



  1. White R Sound Control in the NICU. Pediatrix.
  2. Slevin M, et al. Altering the NICU and measuring infants’ responses. Acta Paediatr. 2000;89(5):577-581.
  3. Raman TS. NICU environment: A need for change. Indian Pediatr.1997;34(5):414-419.
  4. Blackburn S. Environmental impact of the NICU on developmental outcomes. J Pediatri Nurs.1998;13(5):279-289.
  5. Bullough J, et al. Light and magnetic fields in a neonatal intensive care unit. Bioelectromagnetics. 1996;17(5):396-405.
  6. Nair M, et al. NICU Environment: Can we be Ignorant? Med J Armed Forces India. 2003;59(2):93-95.
  7. Pereira FL, et al. Handling of preterm infants in a neonatal intensive care unit. Rev Esc Enferm USP. 2013;47(6):1272-1278.
  8. Hunt K. The NICU: Environmental Effects of the Neonatal Intensive Care Unit on Infants and Caregivers. Southern Illinois University Carbondale 2011.

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