Welcome, I just joined yesterday! I totally sympathise with you, almost every day for the last 3 years I have been lying awake thinking I could so easily phone in sick having had little/no sleep and feeling thoroughly exhausted and as if I've lost the plot. My manager referred me to Occupational health who supported me in terms of a listening ear (which was greatly appreciated), I was given the option of reducing my hours but to be honest it would have increased my stress/anxiety levels as noone else to cover. Fan in the office which is almost constantly on, even in the winter! I am starting a 6 week (1 afternoon a week) woman's wellbeing group through work it gives advice from dieticians, excercise group and trials of different therapies, it was recommended by a colleague - looking forward to it. It would be worthwhile seeing if there is anything local to you for support. I hope you get a positive response from your boss.