I too am getting hot flushes during the day and night. Much to the amusement of my girlfriends as I am only 37 so menopause is not really on the radar at my age but chemo has put me there. We have a bit of a laugh when I flush as I break out in a sweat and start fanning myself...I laugh along with them and say you wait, your turn will come and I can have the last laugh!
During the night I wear light cotton shorts and a singlet to bed as I find I'm constantly throwing the sheet off trying to cool down, so my husband he has been suffering with the fan on too. I haven't found taking tamoxifen any different in the morning or at night. It's weird because I normally really hate being cold or even cool but now Im relishing coming into winter and cooler nights - hallelujah!