All mommas know how important sleep is, but we're also hardwired to respond to our baby's cries. If momma and baby are struggling to get sleep, will it be harmful to sleep train baby? Short answer: no, once they are old enough.
A bit of background: "Sleep training" is the term used to describe a spectrum of approaches parents use to help babies learn to fall asleep by themselves. This refers to a variety of different techniques, including:
The infamous "cry-it-out" method (full extinction). Parents leave baby to self-soothe with no intervention.
The more gentle "check and console" method (graduated extinction). Parents respond to baby's cry at increasing time intervals.
The "bedtime fading" method. Parents put baby to bed late (taking advantage of baby's powerful physiological urge to sleep), then gradually adjust time to sleep over several days to reach the preferred bedtime.
The “camping out” method. Parents sit with baby until asleep, gradually decreasing presence over time.
What does the data say? Some studies investigating sleep training measure cortisol, the body's main stress hormone. A small, but oft cited, 2012 study looking at cortisol levels in 25 mom/baby pairs during a full extinction sleep training program concluded that even though babies stopped crying on the third day, cortisol levels “remained high” (Middlemiss et al., 2012). This study made some question whether all sleep trained babies are suffering, but merely in silence. Closer examination of this study reveals a number of issues, however. First, and most glaring, the infant cortisol level in this study never changed. This means that even before initiation of sleep training, the babies in this study were stressed compared to babies sleeping at home. Why might that be? Perhaps because this study was conducted with mommas and babies at a test facility, not at home, and the babies were put to bed my a nurse, not mom (Middlemiss et al., 2012). The high stress level could be due to sleep environment independent of sleep training. More recent studies provide a different picture. In a study measuring baby sleep patterns and stress levels both during home sleep training (start age 6-16 months) and a year later, it was found that "both graduated extinction and bedtime fading provide significant sleep benefits above control, yet convey no adverse stress responses or long-term effects on parent-child attachment or child emotions and behavior" (Gradisar et al., 2016).
Sleep training baby may also be helpful for mommas, with data demonstrating that implementing "check and console" or “camping out” methods at 7 months led to fewer reported baby sleep problems and less maternal depression at 10 and 12 months (Hiscock et al., 2007).
If you are interested in sleep training, it's important to start at an appropriate age. A systematic review of the literature by Douglas and colleagues demonstrated that sleep training prior to 6 months has "not been shown to decrease infant crying, prevent sleep and behavioral problems in later childhood, or protect against postnatal depression." Worse, it may "risk unintended outcomes, including increased amounts of problem crying, premature cessation of breastfeeding, worsened maternal anxiety, and, if the infant is required to sleep either day or night in a room separate from the caregiver, an increased risk of SIDS" (Douglas et al., 2013).
Worried that decreasing baby's nighttime calories will negatively affect growth? It sounds counterintuitive, but making baby go longer between nighttime feeds may actually be beneficial for growth. This is because prolonged insulin (which is released after baby eats) inhibits growth hormone (Xu et al., 2009). It is not clear what time between feeds could cause "prolonged" insulin levels, but "by 6 months, almost all healthy babies are physically and neurologically able to go 12 hours without food” (Barnett).
So if you decide to sleep train, you can do so knowing that evidence suggests baby will be just fine! And if you'd like to keep an eye on baby while you're in another room, the Eufy Video Baby Monitor provides a local video feed (no WiFi feed that can be hacked) with great signal range, clear video quality (both day and night) and decent battery life.
Sources:
Middlemiss W, Granger DA, Goldberg WA, Nathans L. Asynchrony of mother-infant hypothalamic-pituitary-adrenal axis activity following extinction of infant crying responses induced during the transition to sleep. Early Hum Dev. 2012 Apr;88(4):227-32.
Gradisar M, Jackson K, Spurrier NJ, Gibson J, Whitham J, Williams AS, Dolby R, Kennaway DJ. Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial. Pediatrics. 2016 Jun;137(6):e20151486.
Hiscock H, Bayer J, Gold L, Hampton A, Ukoumunne OC, Wake M. Improving infant sleep and maternal mental health: a cluster randomised trial. Arch Dis Child. 2007 Nov;92(11):952-8.
Douglas PS, Hill PS. Behavioral sleep interventions in the first six months of life do not improve outcomes for mothers or infants: a systematic review. J Dev Behav Pediatr. 2013 Sep;34(7):497-507.
Xu J, Messina JL. Crosstalk between growth hormone and insulin signaling. Vitam Horm. 2009;80:125-53.
Barnett, Natalie, PhD, Grad. Cert. Sleep Sci. “Night Weaning 101 – When and How to Night Wean.” Interview by Kate Web. 8 Feb. 2017, https://www.nanit.com/blog/night-weaning-101/.