Shift Your Body Clock. With Light.

Your body has an internal clock that drives many biological functions, including sleep.

How It Works

When you view light in the morning, your clock shifts earlier — but only if that light falls near dawn. Light in the middle of the day barely moves the clock at all.
Light closest to the temperature nadir — two to three hours before your normal wake time — produces the biggest advance.
When you view light in the evening, your clock shifts later.

If you want to wake up earlier, get morning light. If you want to wake up later, get bright light in the evening.

PS. Light is input. Use it wisely.