Pursuant to the lessons in "Better Sleep, Better You", I am focusing on light &
temperature. I have done various things in attempts to improve my sleep: take
a good magnesium supplement right after dinner; eat a smaller dinner but still
with adequate protein; avoid TV (when I had one) and computer use before bed;
use a bluelight filter on my phone (I have this on permanently anyway); 
restrict coffee consumption after lunch; &c...but somehow, I neglected the two 
most influential variables: temperature & light.


Light
I bought a remote-controlled LED light bulb for about 11$ at Target. With the
remote, I can dim the bulb as the evening goes on - the potentiometer is 
directly in the bulb so I can adjust the brightness no matter what socket it's
in.

Experiment: Dim the light to its minimum setting at 19:30, with a target sleep 
time of 21:00. Progressively adjust the brightness in the hours leading up to 
that to simulate the sun gradually setting.


Temperature
My entire life, I always wanted that "cozy" feeling of being very warm in bed.
Turns out my core needs to drop a few degrees Fahrenheit for optimal sleep.

Experiment:
Wear shorts when going to sleep. If no change is noticed, wear a T-shirt also,
even in the winter. Keep thermostat at 70F. If no change is noticed, drop
thermostat to 65F.