What do I call someone who appears never to sleep, always responding to emails etc whatever the time of day?

  • workaholic is what first comes to mind.
    – Centaurus
    Sep 11, 2016 at 23:36
  • may be dependable, if he is always available when needed
    – user13267
    Sep 12, 2016 at 7:07
  • 8
    Jon Skeet
    – dotancohen
    Sep 12, 2016 at 7:50
  • 3
    Why does the moderator note under the question pertain to answers, rather than questions? Anyway, 'ever-vigilant' or 'insomniac' both might answer the question, and as can be seen, those are two strikingly different words: that's one reason single-word-requests require an example sentence (in most cases) with a blank where the desired word might fit.
    – JEL
    Sep 12, 2016 at 7:50
  • I would call them a machine. Sep 12, 2016 at 15:47

10 Answers 10


I would call them vigilant:

  1. keenly watchful to detect danger; wary
  2. ever awake and alert; sleeplessly watchful.

The word conjures up images of guards ready to respond to danger or trouble.

  • Vigilance is something that's usually temporary and/or scheduled. For example, guards are vigilant, but only when on-duty. Sep 12, 2016 at 2:11
  • 8
    To match the question posed by the OP I'd modify this slightly to be ever vigilant Sep 12, 2016 at 9:36

Depending on context you may use ,"a type A guy" "a workaholic" or "an automaton"

  • type A personality Type A individuals are described as ambitious, rigidly organized, highly status conscious, can be sensitive, care for other people, are truthful, impatient, always try to help others, take on more than they can handle, want other people to get to the point, proactive, and obsessed with time management. People with Type A personalities are often high-achieving "workaholics" who multi-task, push themselves with deadlines, and hate both delays and ambivalence.

  • a workaholic is a person who chooses to work a lot : a person who is always working, thinking about work.

  • an automaton behaves or responds in a mechanical way, a person who acts mechanically or leads a routine monotonous life.

  • 3
    just FWIW, I don't see "type a" cliché as - necessarily - being a "long-hours" type. In some cases, your "type A" businessperson, is one of those "ultra efficient, time management" types that believes long hours does not equal efficiency" - you know what I mean? in contrast to the say "salaryman" type: who chooses to be the "last to leave" everyday, in an effort to prove worth, even if they're actually a bit hopeless...
    – Fattie
    Sep 12, 2016 at 5:25
  • @JoeBlow "...a bit hopeless", you say. This sounds like English (British) understatement. Omit the BIT! Sep 12, 2016 at 6:11


Adjective - Having or showing a capacity for persistent effort; not tiring or relenting.


May I suggest indefatigable as referenced by Hilary Clinton's aura of being indefatigable which slipped yesterday when she had to cut short her attendance at the nation's annual New York commemoration to the victims of 9/11. She was caught by her Secret Service agents in mid-faint and taken to her daughter's apartment nearby. Secretary Clinton's physician, Dr. Lisa Bardack, issued a statement released by Mrs. Clinton's office confirming that she (Mrs. Clinton) had been "...diagnosed with pneumonia...She was put on antibiotics and advised to rest and modify her schedule."

The text in quotation marks reported by The Telegraph online 12 September 2016.

indefatigable: Able to work or continue for a very long time without becoming tired. (M-W)


As a person well-known by his colleagues for responding to emails 24/7, I offer the following:

workaholic: a person who compulsively works hard and long hours [Google]

Some might add an element of obsessive-compulsive behavior:

obsessive-compulsive: denoting or relating to a disorder in which a person feels compelled to perform certain meaningless actions repeatedly in order to alleviate obsessive fears or intrusive thoughts, typically resulting in severe disruption of daily life [Google]

  • While it may be okay to cite Google as your source for definitions, it may be even better to actually visit one of the google results and use that site as your source for definitions. For simple words, Google almost always uses definitions from Oxford Dictionaries Online.
    – NVZ
    Sep 12, 2016 at 0:20

I'd call them a night owl.

Fig. someone who stays up at night; someone who works at night

[McGraw-Hill Dictionary of American Idioms and Phrasal Verbs via The Free Dictionary]

  • 2
    night owl I'd take to mean someone that prefers to work at night but not at mornings (the reverse would be a lark or a morning person), so it doesn't really match the 'any time of day' requested by OP Sep 12, 2016 at 9:38


Constantly, regularly, or habitually active or occupied: diligent.

An industrious worker.

Merriam-Webster Dictionary


Heimdall? :)

Or ever-vigilant.

But those more relate to the request in the title.

Add the email bit, and I'd suggest ever-connected.

  • Please explain how Heimdall answers the quesion.
    – Andrew Leach
    Sep 12, 2016 at 21:43
  • Heimdall is a Marvel comics character that can see everything all the time.
    – DCShannon
    Sep 12, 2016 at 23:46

A Robot seems accurate - question is though - are the email responses accurate and relevant each and every time?

  • Welcome to ELU. Did you miss the post notice about explaining your answer?
    – Andrew Leach
    Sep 12, 2016 at 21:44

Argus fits this description. See https://en.wikipedia.org/wiki/Argus_Panoptes

In the 5th century and later, Argus' wakeful alertness was explained for an increasingly literal culture as his having so many eyes that only a few of the eyes would sleep at a time: there were always eyes still awake.

  • 2
    I'm not sure if this really fits. If you can find evidence of its usage in the context, it would greatly improve your answer.
    – Laurel
    Sep 12, 2016 at 2:00
  • while an interesting suggestion, this isn't really the sense meant by the OP
    – Fattie
    Sep 12, 2016 at 5:27
  • 1
    I'm sure people of the 5th century would get it, it doesn't really work in contemporary English. Sep 12, 2016 at 8:42
  • Well, I can imagine Boris Johnson using it, althought might need an explanatory comment as well. And of course, Brighton has a certain local newspaper.
    – Andrew Leach
    Sep 12, 2016 at 9:09

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