Okay so I take naps after work every week day but, for some odd reason on Fridays i always wake up with a huge headache feeling really dehydrated and sometimes my body is like shivering/vibrating. Now I work a normal week Monday to Friday and this almost never happens on any other days but Friday. I don't do anything different I do the same amount of work as any other day, I eat the same lunch and have the exact same routine. I've even tried drinking a good bit of water before napping but it didn't make much of a difference. Could anybody tell me what I can do at this point to prevent this? Or even just tell me why this might be happening would be great.