No idea what's normal or not, but why not speak to your boss about it and consider doing hours reduction?

When you get stuck on something, it is quite good to move onto something else for a time before coming back to it.

Maybe you are suffering burnout. Maybe it's a case of imposter syndrome. Maybe you are not meant for the modern workplace (a lot of people aren't). Maybe you don't like your particular environment. In any case, take some time when you can and figure out for yourself how you really feel about stuff like that. Write it down to think better.

Just look busy and it will be OK. You appear to be in a place that values warm-bodies-at-desks rather than actual work product.

@TymoteuszPaul: hours reduction, while a good idea in itself, is only a last resort option. It usually sends the message that failure is accepted, and that is most likely not the case.

How much do you sleep each night? Could you take a nap mid afternoon and lengthen your workday? What do you eat for lunch?

Install a blue-light filter such as f.lux, and set it to a fairly low setting. You'll find that it does wonders for your eyes, and by extension, help you focus a little later in the afternoon. Getting enough rest, and maybe working out will help with you as well.

@AndreiROM If using Windows 10, it has a built in setting for that.

Maybe you should tell us -- by editing your question -- how your work day is broken up into various breaks. We all need them in order to stay productive.

@AndreiROM I use blue-light filters permanently on my home computer (and phone), but during daytime in a properly-lit environment like an office they seem a lot less useful or necessary (and possibly counter-productive, but that's a bit speculative).

@AndreiROM - You should probably clarify: you're talking about doing that on a computer at home that you're using late at night. Putting a "help you go to sleep easier" filter on at work when your problem is "I can't seem to stay awake" probably isn't a good recipe.

Are you actually falling asleep or are you simply mentally tired (i.e. unable to focus, but otherwise alert)? While those two issues may have some common causes, they're largely disconnected and the answers would (or should) be quite different for each.

Well, you know what the old philosopher said: youtu.be/9Ht5RZpzPqw?t=79 :D Nah, seriously, I've been there, it's difficult knowing you still need to work a couple of extra hours. As others said, just pretend you're actually busy. And don't expect a lot from your manager, you'll get a better one eventually in your career. Best of luck!

I don't have enough cred to answer here, but I'd like to add that there has been a massive amount of research lately on this very thing. The general takeaway is that (especially for software engineers) anymore than 4 to 5 hours per day is worthless, and often counterproductive. In fact, it's pretty common for the mistakes made in the last 3 to 4 hours of an 8hr work day to nearly negate the productivity made in the first 4 to 5 hours. You're not alone here man. This is human biochemistry/neurology at work.

Yes, it's very normal. Many of us can't work for a full 8 hours a day and instead spend time doing other things like answering questions on stackexchange.

What exactly did your manager notice? It's extremely hard to notice when a dev isn't being productive for 2> hours at a time, so it's hard to imagine what you did to get noticed...

Not being able to solve a specific problem in the last 1-2 hours of the day does not mean you are not working the whole day.

Seems a bit like my internship, but I worked 42h per week for low pay, so maybe that's a factor...

Related blog post on stackoverflow.blog. The important here is: Very few people are writing code for more than 4 hours a day.

I have always been the same at the end of the day. I call that the "negative work zone" becasue I can actually do more harm than good! Like you, I find also that the next day, it is almost always solved in 5 minutes. My best strategy (whenin an non-so-understanding environment) has been to save dull admin type tasks for such times.

Welcome to the autocracy and exploitation of capitalism.

If you can get away with it, a 30 minute nap in the mid-afternoon can be really helpful towards allowing you to be productive for the remainder of the workday.

If you are most effective in the morning, and tired early in the afternoon, you could have an earlier than "average" sleep phase (google: chronotype). Do you easily get up very early? Are you even awake hours before you go to work? If so, then (probably) bingo. Maybe you could go to work earlier, unless there is a trust issue wrt you being there before most/all others...

Just pretending to be busy. That's what I do every afternoon (And that's also what my manager/lead does). Usually I feel exhausted and tired starting at 15.00-15.30. I can't afford to go further.

Ritalin/Adderall

I think many people here might be misunderstanding OP. I don't think the problem is just that he can't actively work 8 hours a day. I think his mental health suffers when he's at work for that long, even if he isn't actually doing anything. Sadly this isn't exactly uncommon, but it won't be considered "normal" either. It's roughly the situation I am in.

@Granite Do you have flexible work hours? "get it done in 5 minutes the next morning" suggests you may be a "morning person" who can be very productive early in the day, and therefore should start (and finish) their workday early if possible. I am the opposite: Usually not much of a productive software developer before noon, but I can get quality work done until 9-10pm.