Every time we get a ping indicating a new email, comment, or notification of any sort, our brains get a dopamine hit. Dopamine is the neurotransmitter responsible for feelings of reward and pleasure, and it can get addictive. This is why it’s so easy to succumb to constantly checking your emails, as each new message, however mundane, releases dopamine, at the cost of productivity. Combat this by scheduling set times to check emails, and allocate other times to producing your best work.
Source: learn.filtered.com