During the first year of life, infants spend most of their time sleeping. An infant can go through several periods of change in sleep patterns. These can start at 1 week, occurring weekly or fortnightly, until 8 years of age due to innate and external factors that contribute to sleep.Developing infants also sleep within a large spectrum of sleep — falling into high and low needs categories — fragmented through 24 hours.These frequent night awakenings are an evolved trait, to feed frequently and playing a part in SIDS protection. However, this can be disruptive for the parent(s) or caregiver — for example, if maternity leave is non-existent or they feel the benefits of an undisturbed night can help with severe sleep deprivation. Parents who sleep trained perceive improvement in infant sleep.