It's just gone 6 o'clock in the morning and my circadian rhythm is messed up in spectacular fashion. The altitude, 14,000 feet, doesn't help nor does being outside when the body is so tired yet the sun is rising, it just confuses one further and despite not having slept for a good 16 hours, the sunlight tells your brain it's time to wake up. No wonder sleeping during an observing run on Mauna Kea is a very difficult thing to do!
Usually, for the first couple of days I have real problems getting sufficient rest and the times I do sleep my dreams are extremely vivid and often wake me up. After a couple of days, though, you are so tired that sleep comes a little more easily and you start to settle into the new rhythm. Unfortunately, my schedule often involves just the odd one or two nights at the summit separated by a few days, so my brain never really gets its act together. Some tell me, however, that they see no difference between these times and when I'm off the mountain for a while...
Even the observatories have to be put to bed at dawn. Above, Gemini and UKIRT are closed after a night spent observing the cosmos although the daytime engineering crews will be up shortly to work on the various mechanical, electronic and computer equipment - there is always work that needs to be done on the observatories' complex systems whether it's fixing a problem, maintenance or improvements.
The telescopes down in Submillimeter Valley often work into the daylight hours as the wavelengths they work at are not affected by sunlight in the same way as the optical-infrared telescopes. Despite that, even those observers have to sleep at some point!
As ever, you can click on the images to see larger versions.