<human>: Can you summarize the given text in a few sentences?

Usually I start work after my two co-workers, they're here to open up, and then I stay and lock up at the end of the day. I'd arranged to swap shifts with one of them today, but had skipped my lunch break earlier in the week so I could still start at the later time as usual, just leave an hour earlier. 

This morning I woke up to a text from my co-worker (the only one who was left opening today) to find that he's sick and won't be coming in, so could I go in and open up seeing as the other was starting later and working my regular shift time? That wouldn't have been a problem if I'd received the text earlier, but I live over an hour away from work and definitely wouldn't have made it in time to unlock the building. I texted the co-worker I'd swapped shifts with to let him know that I'd be there as soon as I could, and that no one would be there to open up, so the building might be locked when he got there.

At this point, it's probably a good time to mention that morning me is not a reliable person. So morning me, still half asleep, falls back asleep, assuming that my alarm will wake me up. Only, my alarm had already gone off, so I actually had no alarm set. I woke up 10 minutes before I usually start work, and ended up over an hour late this morning. The co-worker I had 'swapped shifts' with had come in early to open up and was planning on going home once I got there, but is now working the entire day from open til close (around 12 hours), and I feel like a dick.
<bot>: Slept in and was over an hour late to work on a day that I was already finishing an hour early, leaving a co-worker to work a 12 hour day.