Why is my sickle cell pain worse in the middle of the night?

Several reasons....: Vasoocclusive crises occur when transit time through a capillary bed exceeds sickling time. Conditions that shorten sickling time (eg., acidosis, hypoxia, dehydration, hgbs conxentration, etc) or lengthen transit time (eg., reduced perfusion) exacerbate sickling and its sequelae (including pain). These are all true at night. Also, distractions increase awareness of pain, contributing to this sense.

more info is needed: More information is needed--specifically--where is your pain? Are you drinking enough fluids and are you in a cold or chilly environment--may try extra blanket--if this is a chronic pain issue, you should explore with your M.D.

Night is harder!: There have been a few studies that showed that hospital admissions and emergency department visits for sickle cell pain were more frequent in the evening and night, so you are not imagining this. It might be that you are less distracted and so feel the pain more than during the day. You might have 'overdone it' during the day. Ask your doctor about Hydroxyurea if you are not already taking it.