The New Yorker – E-Mail is Making Us Miserable – by Cal Newport. “…To study the effects of e-mail, a team led by researchers from the University of California, Irvine, hooked up forty office workers to wireless heart-rate monitors for around twelve days. They recorded the subjects’ heart-rate variability, a common technique for measuring mental stress. They also monitored the employees’ computer use, which allowed them to correlate e-mail checks with stress levels. What they found would not surprise the French. “The longer one spends on email in [a given] hour the higher is one’s stress for that hour,” the authors noted…Much in the same way that our attraction to food is coupled with the gnawing sensation of hunger in its absence, our instinct to connect is accompanied by an anxious unease when we neglect these interactions. This matters in the office, because an unfortunate side effect of overwhelming e-mail communication is that it constantly exposes you to exactly this form of social distress…A frenetic approach to professional collaboration generates messages faster than you can keep up—you finish one response only to find that three more have arrived in the interim, and, while you are at home at night, or over the weekend, or when you are on vacation, you cannot escape the awareness that the missives in your in-box are piling up ever thicker in your absence….To return to our motivating question, there are many reasons why e-mail makes us miserable. It creates, for example, a tortuous cycle that increases the amount of work on our plate while simultaneously thwarting, through constant distraction, our ability to accomplish it effectively…”

See also Wired – Email and Slack Have Locked Us in a Productivity Paradox “…But at the same time, we feel increasingly overwhelmed and frustrated by the sheer number of hours we now spend engaging in this streamlined back-and-forth messaging. Once we removed the cost and friction from office interactions, the quantity of this chatter skyrocketed. According to various studies I gathered during my research, in 2005, we were sending and receiving 50 emails a day. In 2006 this jumped to 69. By 2011 it was 90. Today we send and receive an estimated 126 messages, checking our inboxes once every 6 minutes on average…”