When your foot is falling asleep quite regularly and it is the same foot despite different positions and even days, it could be a sign of something else that is affecting the foot. Generally, some of the common problems can include either vascular compromise or nerve damage, either of which can be reversible or temporary, or may even be related to the way that you frequently hold your foot. For example, people who habitually cross their legs are subject to some nerve changes that can make their feet fall asleep more readily, which then reverse quickly when the behavior is adjusted. In others, such as diabetics or those with a long smoking history, the feeling of feet falling asleep can be a sign of some difficulty in getting blood down to the feet due to vascular problems. Alternatively, early signs of nerve damage, again due to poor vascular supply to the nerves themselves, can begin to present in this fashion. Given the wide range of causes and the need to analyze your physical exam and other concerns, you can see why it is important to speak with your doctor
about your problem if it persists. Please talk to your doctor.