The Overnight Shift and Sleep Cycles

Whew!  What a whirlwind!  Put in two 11pm-7am shifts security as per usual at the Claridge, and, after sleeping 8am-3pm, gonna do three 7am-3pms this week, starting tomorrow!  'Twas against my better judgment, taking this on...really wanted to just work evenings and nights, but, if they only have mornings, I'll do it...just need an extra day to recoup the sleep and get back on waking up in the mornings schedule, but I'll turn in early tonight and get 'er done.
Starting next week, will begin a third 11pm-7am regular shift.  This is good, because it'll help my body and mind get acclimated to sleeping in afternoons. 
Gotta be careful and get 8 hours of sleep every day, because if I only get 5 or 6 hours, as was the case Wednesday, I get the WORST headache...feels like the worst hangover you can possibly imagine.
So this is good...winding down for the inevitable crash tonight...wanted to squeeze a bike ride and workout in, but the rain outside is making that prohibitive.  Tomorrow evening perhaps...