What Could Be the Reason?

Gluten does that to me. When I went gluten free, my mind became so much clearer (as did my gut). "Gluten fog" is a known problem.

Could also be depression. It's a lot easier to surf the web and pay attention to nothing than it is to deal with real stuff that needs to be done. Worth seeing a doctor about possible depression.

Depending upon your age, hormones will do that.. A drop in Estrogen levels can really give you that brain fog.. Estrogen controls the feel good hormone, serotonin... when estrogen drops... ugh... our feel good "ness" kinda drops along with the serotonin...estrogen also controls cortisol, the stress hormone.. when estrogen lowers................ cortisol can run amuck... hence..your focus is lower........your mood is lower BUT... you may still be feeling stressed due to the higher cortisol..
however, in terms of an internet addiction.. could be that too.. i tend to think our dilemmas get worse at certain times of the month... i don't mean to sound cliche' but it's true.. so IF you are prone to surfing the net.. notice if this happens more or less at certain times of the month. for me... nearing my period and at onset... when estrogen is lowest. I feel down... nervous (because cortisol is up) which means I also can't sleep.... and that too causes a problem.. so if I have bad habits..which I do.. then they manifest themselves more so around that time..

Could be depression or peri-menopause.
It could also be a hypothyroid problem - 'brain fog' is common when your thyroid is low functioning.
Might be a vitamin D deficiency - the winter blues - a SADD light might help you out if that's what it is.
It might also be not enough B12.
See your doctor and have a physical.

Internet addiction exists. A qualified counselor can help you determine if that is what your problem is, or if wanting to spend time on the internet is just a symptom of another problem. With some work, and counseling, you can recover your focus and get more engaged in life.

Best,
F. B.

Could it be laziness? I know I have been suffering from that lately. Not wanting to do the dishes, laundry, get ready, cook dinner, or go to the store. Sometimes I think we tend to over-analyze some things that are just flat out laziness. The computer is a nice rest point where we can check out and do things we don't HAVE to do. I know I have become quite a shopping addict. What are you doing online? Are you shopping? I am a shopping addict. It used to be the mall, but now it's the internet that I use to shop. :-) I'm not saying that it's not possible that you have some depression or hormone imbalances that are making it more difficult for you to focus, that could be the case. As for the not being able to focus on a task, what tasks are you doing? If they are the mundane household tasks that you have to do everyday, it's no wonder because that stuff is usually boring.

Here's some advice! Get up and just make yourself start something. I find that if I can just get started it's a lot easier to get motivated to do more. Turn off the computer. Silence notifications from computers and phones. Only check your phone every once in a while. Like maybe 4 times per day. You gotta kick your own butt because as grown ups nobody kicks it for us. (unless you have a controlling spouse or something, LOL)

Good luck! Just know, I am out there too and am struggling with the same thing, so it's like we're working on it together, right! LOL

Definitely sounds like depression to me. The internet is an easy escape from the way you're truly feeling.

Go see your doctor - rule out any imbalances. Take vit Bs&D. Get outside and go for a walk. Eat fresh, healthy food. Get enough sleep.

Could it simply be the business and distraction of the holiday season?