Particular embodiments provide power usage management for network devices according to historical traffic pattern data. Network traffic statistics for traffic flowing through a network device may be determined. A traffic pattern for a time period based on the traffic flowing through the network device is then determined. The network device may then manage power based on the pattern. For example, when a pattern indicates that traffic flowing through the network device is light during a time period, then the network device may operate in a lower power mode, such as a standby mode and when it indicates that there is higher usage, the network device may operate in a normal power mode. In one embodiment, a power usage policy may be determined based on the historical traffic patterns and is automatically enforced by the network device. The power usage policy may also be dynamically adjusted over time based on network traffic statistics.