Slumber is a Chrome extension that transforms your new tab into a beautiful sleep time calculator. Developed by Dan Hayes, this free program replaces your "New Tab" screen with a sleep calculator and the current time, aiming to help you feel rested and energized in the morning.

With Slumber, all you need to do is set your wake up time, and it will suggest the ideal times for you to fall asleep. The extension calculates sleep times by counting backwards in sleep cycles, which consist of periods of deep sleep and REM sleep lasting about 90 minutes each. By falling asleep at one of the suggested times, you can ensure that you wake up in between your sleep cycles.

Waking up in between sleep cycles allows your mind and body to feel more refreshed in the morning, leading to improved energy, mood, and mental sharpness. Slumber is a simple and straightforward tool that aims to make waking up just a little less terrible.