If you need a large download to complete overnight, sleep mode is your enemy. Instead, you have three practical options:

Standard sleep on a Mac stops all network activity. To keep downloads active:

Second, , such as a NAS (Network Attached Storage) device or a Raspberry Pi. These are not your main computer. You can initiate a download on your laptop, then put the laptop to sleep, but the download will fail unless the other device (the NAS) is actively doing the downloading. Your computer merely told the NAS what to fetch; the NAS continues the work independently.

The only component that typically remains active is the RAM (Random Access Memory), which retains your open applications and their current states using a trickle of power. This allows for a "quick wake"—pressing a key or moving the mouse restores your session in seconds. However, because the network adapter is asleep, it cannot send or receive data packets. Any ongoing download, whether in a web browser, a game launcher like Steam, or a system updater, will immediately stall the moment the network connection dies.