

Just use the Color Temperature slider in the Displays settings. Schedule: Create a custom Night Shift schedule or set Night Shift to turn on automatically from sunset to sunrise. You can also set how much your display colors shift towards red when Night Shift is active. Make sure your Mac meets the system requirements for Night Shift, then follow these steps: Choose Apple menu > System Preferences. Schedule Night Shift and control its intensity in the Display System Preferences Set when Night Shift runs from the Schedule pop-up menu.Go to the Apple menu and choose System Preferences.Sorry gang, older Macs don’t get Night Shift To schedule Night Shift on your Mac do this: Swipe down just like you do to show the Do Not Disturb setting.Click the Notifications icon at the right edge of your Mac’s menu bar System meets the requirements for Night Shift Website Shifting supports Safari, Chrome, Opera, and Vivaldi True Tone features require a supported Mac and macOS 10.

Night Shift has been a part of iPhones and iPads since iOS 9.3.
NIGHT SHIFT FOR MAC INSTALL
As you cannot get Night Shift for your Yosemite install you might like to try Flux, an app people have been using for a while and does the same job as Night Shift and is a bit more more flexible, you can get it here, https.

Night Shift is not available prior to macOS 10.12.4. Sunrise to sunset this will the most preferred option if you want to your Mac to schedule the night shift from evening to morning daily. With Apple's Night Shift feature, the colors of your display are shifted to the warmer end of the spectrum during the evening hours. Upgrade to macOS Sierra if your Mac is compatible. To manually activate Night Shift on your Mac do this: Mac will enable the night shift mode everyday only during the scheduled time. In case you want to manually enable or disable the Night Shift mode, all you have to do is to click on the Notification Center (its the icon with the three. It’s easy to activate, so follow along to learn how. Apple added Night Shift support to macOS 10.12.4, which is currently available as a beta. Night Shift-the feature that slowly shifts your display color temperature as the sun sets–has been available on the iPhone and iPad for a while, and now it’s coming to the Mac.
