After Harvard University published an article about the ill effects of the blue light being emitted by all the LED based screens like that of your laptop or mobile phone, things started to get changed. All the major operating system slowly started to include a dark mode or night mode in their settings. Android and Windows were the first ones to include the night or dark mode. Pretty soon Apple followed the suit and also included a dark mode in Mac OS starting with Mac OS Mojave. This dark mode can bring down the screen brightness and make the screen put much less stress non your eyes, especially if you work with your Mac at night time in dark surroundings.
A free app called NightOwl can make using the dark mode in Mac OS much easier. Usually, you have to take many steps to toggle the dark mode on or off in Mac OS : you have to open the System Properties, open the General category and then choose Appearance type to be either Dark or Light. You can avoid all these steps if you use NightOwl which places an icon in the menubar itself. From this NightOwl shortcut, you can quickly open NightOwl that allows you to switch to Light or Dark appearance mode in a flash. Additionally, it also offers a hotkey that can be used to toggle between the dark mode and the light modes.
Furthermore, it also allows you to schedule the switching of the appearance modes at pre-specified times. You have to choose the time at which it should automatically turn on the light mode and the time at which it should switch on the dark mode. You can also choose to toggle the modes automatically at the sunrise or sunset times for your location (it fetches the sunrise/sunset times from the internet).
You can download NightOwl for MacOS from https://nightowl.kramser.xyz/