Insomnia Support Group
Insomnia is a symptom, rather than a disease, and is characterized by inadequate quantity or quality of sleep. People with insomnia complain of difficulty falling or staying asleep, which results in significant impairment of daytime functioning. Insomnia is categorized as transient (shorter than one week), short-term (one to three weeks) or chronic (longer than three...
As for light, you should keep the room as dark as possible. I have read from sleep experts that if you can see your hand in front of your face then you have too much light. Even small nightlights can cause problems. Since "zero" light can be difficult, a sleeping mask may help.
As for drugs, both Rx and OTC, many of these can cause sleep problems, even OTC stuff. I know this from personal experience. Both Rx and OTC meds have wrecked my sleep, especially REM sleep. If you are taking anything at all, even during breakfast, try stopping (if possible) for a couple days to see if you experience any sleep changes. I know this sounds "out there", but I have had problems with OTC (and Rx) drugs, taken in the morning, that slowing wrecked my sleep. It can be very difficult to weed out the offenders.
The light is a good issue, I do try and keep my room as dark as possible, but moonlight does creep through. And I used to enjoy moonlight! ;).
In addition to what you've described, you might benefit by working on your your sleep schedule. Your consistent wake-up time is good. I suggest keeping that 7 days a week if you are not already doing so. Trying to catch up on lost sleep on weekends tends to worsen the problem. Consistency is important.
You might try conservatively cutting back a bit on the time you allow in bed. This should have the effect of naturally ramping up your homeostatic sleep drive.
So for instance if you're averaging 6 hours of sleep, you might try scheduling no more than 6 or 7 hours in bed and see what happens. If your sleep improves but you're feeling daytime fatigue, try adding in a bit more time. By making gradual changes, and by giving yourself a good week or two to adjust, you will eventually find your optimal sleep timing.
This is the basis of sleep restriction therapy, one of the key methods contained in cognitive behavioral therapy designed specifically for insomnia.
Sleep drive, along with your circadian rhythm, are two important physiologic components that largely control sleep. CBT methods give you the tools to manage them both simultaneously so they complement and support one another. By doing this effectively, sleep can become practically irresistible.
Good luck to you.