To change your account details such as your email address, simply log in to your Headspace account here. Go to the 'Account' section of your account and then click on the 'Settings' option.
Once you've entered your new email address, be sure to click on the green 'Save' button at the bottom of the page.
Please note that if you've registered with Headspace using your Facebook credentials (the 'Sign up with Facebook' feature), you will not be able to update your email address via Headspace. You'll need to send us a note at email@example.com for further assistance.