Great thread - I also listened to T.S. Wiley earlier before I read this thread, and it was a treat to read Psyche's scans as I have a few other books on my list before I get to Wiley's.
I am in Northern Europe, beyond the 60th north latitude, and definitely I need less sleep in the summer. My rhythm gets a bit confused up here. I have darkened my room, somewhere around 98% but I will move to the tinfoil to get 100% darkness.
One way to describe the light here, even though the sun does dip below the horizon in this more southern part of Scandinavia, is that at the darkest time of the night here, you can still drive easily without your car lights on.
I find I hit a "second wind" sometimes from 10PM to 3AM, where there is no way I could try and sleep. If I do stay up past 3AM the day starts brightening dramatically but it seems as if my internal clock does not know if at that time the sun is going up or going down!
It seems in the summer it is also a matter of discipline: I just want to stay up more and enjoy the lovely summer days, as there are so many dreary and dark winter days. So I end up staying up late. I could choose to discipline myself to be in my dark chamber by 10PM (when it is totally light outside), but although relatively rare in my life the sauna nights, festivals, singing and listening to my buddies playing guitar by the seaside tend to get in the way. Even though socializing is relatively rare, I am for whatever reason reluctant to go bed and let the beautiful summer day come to an end.
What I do to sleep in this 'summer of eternal light' is jump into my dark room, and get anywhere from 5-8 hours of sleep.
My energy level in the summer up here is second to none - I should sleep in winter, and do most of my work in summer as I would get way more done
However, if I have had these "second winds" and stayed up late, I usually start feeling less energetic (as it is light outside all night long as I stated). When I feel this way I just go to bed between 9PM and 10PM one night , into my dark room, and I will sleep til about 3AM or so . And due to knowledge from T.S. Wiley and this thread, when I wake up at 3AM, I make sure not to look at any lights, contemplate for awhile, take in a bit of ambient light when I find the toilet and come back, then back to my dark room. Then I may sleep until anywhere between 7 and 9AM.
For example, last night I did EE without Beatha, and fortunately it was a cloudy night so my internal clock started getting me sleepy - by 11:45PM I was in my bed, in the darkened room and I slept till 6:30AM. I woke up for awhile, chatted with my room mate who was making breakfast, then I went back to bed and woke up 10AM! Great life eh? :)
With regular EE, a darkened room, and my low carb diet (I've reached ketosis) one can even get sleep in the land of the midnight sun!!
Jefferson