People often behave differently because they know they are being watched it calls The Hawthorne effect. It can affect all sorts of behaviors such as dietary habits, or hygiene practices because these have considerable opportunity for prompt modification. Also, if a chain smoker realized he is under watch his smoking rate will be lower so sometimes people act positively when they are under watch. It is a human nature that we often try to show our better side to the other. In an example, a study of hand- washing among medical staff found that when they knew they were being watched, the percentage were 55% greater than when they were not being watched (Eckmanns 2006).
Being watched all the time has negative impact as well, it can put an additional pressure on the individual. Like in an office employee are under surveillance all the time so it pushes them to work harder but in a long run it can lead to anxiety. It can changes the way people think and act, causing them to avoid writing or talking about sensitive subjects also discussions that are necessary for the functioning of a free society