Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
Just lack of sleep of it's own should not cause a swelling of the foot. Feet can swell up if say you keep standing for a long time, or even sitting , because fluid pools with gravity and if there is not enough movement, the foot or ankle can swell up. But lack of sleep per se should not have that effect. Depending on if you have pain with it or not, swelling can be because of arthiritis, joint infection, inflammation around the tendons of the ankle or rarely due to a undiagnosed fracture ( especially if you have a history of foot injury or trauma). Swelling of both ankles can be seen in venous insufficiency ( the veins are not doing their job to take the blood back up from the legs, hence resulting in pooling of blood and swelling), heart problems or kidney problems resulting in excessive fluid in the body.
Associated features with your ankle swelling would help one narrow down the possible causes.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. MedHelp is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.