Use Night Shift on Mac
Use Night Shift to adjust the colours on your display to the warmer end of the colour spectrum. Warm screen colours are easier on your eyes when you use your Mac at night or in low-light conditions. Also, exposure to bright blue light in the evening can make it harder to fall asleep.
Note: To find out if your Mac supports Night Shift, see the Apple Support article Use Night Shift on your Mac.
Schedule Night Shift to turn on automatically
On your Mac, choose Apple menu
in the sidebar. (You may need to scroll down.)Click the Night Shift button on the right, click the Schedule pop-up menu, then choose an option.
Off: Prevent Night Shift from turning on automatically.
Custom: Specify the times you want Night Shift to turn on and off.
Sunset to Sunrise: Use Night Shift from sunset to sunrise.
If you select this option, your Mac uses your location to determine when it’s night-time for you. To use this option, you must turn on Location Services. Choose Apple menu > System Settings, then click Privacy & Security
in the sidebar. (You may need to scroll down.) Click Location Services on the right, then turn on Location Services. Scroll down to System Services, click Details, turn on Setting time zone, then click Done.
Turn Night Shift on and off manually
Even if you set a schedule for Night Shift, you can turn it on or off at any time — for example, if you’re in a darkened room.
On your Mac, choose Apple menu
Click the Night Shift button on the right, then turn on Turn on until tomorrow.
Night Shift remains on until the next day or until you turn it off.
Tip: You can also turn Night Shift on and off using Control Centre. Click Control Centre 
in the menu bar, click Display, then click the Night Shift button. You can also use Siri to turn it on or off.
Set the colour temperature
On your Mac, choose Apple menu
Click the Night Shift button on the right, then drag the slider to change the colour temperature Night Shift uses.