A. Milestones & developments
As mentioned earlier, separation anxiety usually occurs when infants are 6-8 months old. During this time, babies are simultaneously experiencing some major developmental milestones -- especially in terms of mobility. For example, they are beginning to learn to roll (even in their sleep) and crawl, and are able to get into the sitting position without help. In addition, their language and communication skills begin to emerge, teething and babbling are all possible during this period, and these are all factors that contribute to sleep regression. Many parents mistakenly believe that their child's poor sleep is entirely due to separation anxiety. But the real cause should be comprehensive, not just because of the emotional rebound caused by separation anxiety.
B. Anxious first-time parents
This is one reason many parents don't notice. People's emotions affect each other, and primary caregivers have a significant impact on their children's emotions. In the first year of being a new parent, we experience uncertainty, fatigue, worry, and even depression. The baby will understand things through our emotions and behaviors, and if the mom or dad is panicked and helpless, they will pass that emotion on to the baby, making them cry even more.
Imagine being in a panic early in the morning when a company supervisor comes into the office with a sad face. The staff would feel bad and tense, wouldn't they?
If the little one does experience a sleep regression, anxious parents may increase the intensity and duration of coaxing or even decide to co-sleep with the baby. This may lead to the development of unhealthy sleep routines and habits, requiring longer hours of coaxing, and eventually creating long-term sleep problems.