Okay, before you start ADDING things, espeically when it comes to insomnia, you need to DELETE everything that could possible interfere with sleep.
Make sure you've cut all caffeine out except for
maybe a cup of coffee first thing when you get up (caffeine is not just in coffee, but tea, cocoa, chocolate, Mountain Dew, and "energy drinks" e.g., red bull, also some pain pills, like Excedrin, contain caffeine). Start reading labels.
Are you on any prescription or over the counter medication or even dietary supplements? Anything that isn't FOOD or DRINK that goes into your body can potentially affect you
Do you live in a city that fluoridates its water? Call the water company and find out (seriously). If so, drink and cook with bottled water exclusively. Some people are sensitive to fluoride and one of the ways it can manifest is sleep disturbance. If you're worried about your teeth I assure you, the way fluoride works is through topical application (in other words, what you get brushing your teeth is the only stuff that affects your teeth). You do not need it, it is NOT a necessary element.
Is your bedroom comfortable? Is the temperature good, the room quiet and well ventilated, is your bed comfortable? Is it QUIET and dark? Do you have a lot of street noise? Noisy neighbors?
You're a cop, are you constantly getting your shift fiddled with? If so, I have NO idea what you can do about that, but that will screw up your ability to sleep. Do some research on the internet about sleep cycles/circadian rhythms/shift workers.
The thing to remember with exercise is that you need to do it early enough in the evening so that it isn't overstimulating. It's better if it's at least 4 or more hours before bedtime.
Finally, I swear by this man's CD's ... you need either a surround sound system in your bedroom, or get a portable CD player with comfortable headphones and play this CD:
http://www.amazon.com/Delta-Sleep-S...B000654YF6/ref=pd_sim_m_5/104-2113356-3990322
(it has to be surround sound or in headphones to work properly)
There are herbal supplements, but the first thing you do is really look at your life in terms of what can be eliminated/improved first.