Comparison of evoked arousability in breast and formula fed infants. (psychologytoday.com)
Extraverts have a low level of arousability — in other words, it takes more stimulation for them to be at an optimum level of arousal. (personalityresearch.org)
Spontaneous arousability in prone and supine position in healthy infants.Sleep 29 (6): 785 - 90. (psychologytoday.com)