These are great, informative posts on this thread. I'd like to chime in as well, as I seem to have more troubles with sleep compared to back in school.
1. Regular routine.
I have been starting this, it is HARD because I usually have to get up at 05:30 and it is dark and cold. In the past I used to stay up very late, watch a movie, type on forums (ha!) , etc... I have read several books about sleep, including "Sleep, It Does a Family Good", "Power Sleep", and others. When your body is used to "awake time" and "sleep time" I am noticing it helps. Otherwise, it's like you are traveling to a different time zone.
2. Sleep environment.
My wife tends to be a restless sleeper; sometimes a random arm or leg is on me, or she talks in her sleep, or once she yanked my pillow away. Then the dog likes to sleep in the bed, and she will walk around or squish into you - disaster for a light sleeper. I have changed to sleeping separately on work days, and it has helped.
Along with bed comfort, I echo the advice about DARK, quiet (use a fan, Dohm sound machine, etc. to drown out noise), cover any led's or clocks, etc. Also be sure you are cool but not too cold. In the hot summer, I can't sleep well upstairs when it's hot.
Ear plugs help too, as does quiet/calm music sometimes (as the posts above mentioned)
3. Transition to bedtime.
I have noticed you NEED 'wind down' time. Turn down the lights (bright light impairs melatonin secretion). Use a program like F.lux for computer screens (it changes color temp to reddish), as blue wavelength light also stops melatonin production.
Reading a little or just focusing on breathing a bit; Dimmer lights help, and also just sitting on the floor to breathe and stretch, +/- some relaxing music. For some, taking a bath/shower at night helps (my grandma does that, she said).
4. Exercise.
I always can add some more exercise. I forget that I can simply walk some more too in addition to weights/cardio/kung fu work. Be careful about not working out hard too close to bed, you won't sleep well. Exercise also helps to 'de-stress' the pressure of the day.
5. Decreasing caffeine / not drinking too late:
Dr. James Maas, author of "Power Sleep" recommends to have no caffeine after 6 p.m. Everyone is different, your body will metabolize it faster or slower, etc. For me, I have stopped drinking coffee or pop at least 4 hrs. before bed and it has helped me. I bet a longer span would work even better.
6. Meds/supplements/etc.
Okay, this could be big alone, but here's what I've tried.
a. No prescription meds yet. I know things can be addicting and I'm trying to avoid that. But I have talked to co-workers and relatives who were helped very much by once in a while use of a benzodiazepine (Xanax, Ativan, etc.) or Ambien/Lunesta, etc.
b. Hormones: lowered testosterone can impair sleep, mood, fat burning, etc. and is a possibility. Same goes with estrogen & progesterone, imbalances can make you either tired or wired. Blood work can be a way to check this.
c. Melatonin: I have tried many variants. I have read that your body typically makes 0.3 mg naturally. Melatonin can make me really hung over, so I only take sparingly. Some companies make 1 mg SL tabs to dissolve on your tongue. I just found one called "MidNite" that is 1.5 mg melatonin quick-dissolve tab. I can use 1/2 to 1 tab. I have noticed less AM hangover. Melatonin is best to only 'reset' schedules vs. taking it every single night.
Of note, tart cherry juice contains a decent amount of melatonin naturally...
d. Minerals: I am sensitive to Magnesium, via trial and error. It is relaxing to blood vessels, the CNS, heart, etc. If I take more than 150 mg of MgCitrate or MgGlycinate I will be hung over. The opposer, so to say, is Calcium. Too much calcium late in the day will make your heart beat stronger and amp you up more, so for me I take a small dose only at breakfast and lunch.
If you are Mg-deficient, though, perhaps 300 mg or more could help, often dramatically. You have to see what you need. Under the "magnesium" section is a supplement called ZMA. 2 caps of that knock me out, but I feel like a zombie the next day.
e. Benadryl (diphenhydramine): some co-workers take this, 50 mg, but I only tried once; my mouth and eyes had all the moisture sucked out, and I was HUNG OVER in the morning. Not for me. Doxylamine is another OTC sedative (Unisom), I haven't tried it.
f. Chamomile caps/tea: I found capsules at Vitacost's website (450 mg). It is a calming agent, you can also get it in tea form and also the "sleepy time tea" to help wind down. I try 1-2 caps in evening sometimes.
g. Valerian: I try this on and off. It is a sedative compound, and is believed to also affect GABA receptors in your brain. It smells TERRIBLE (stinky feet?) but it has helped me sleep PRN. I like Nature's Way Valerian standardized (0.8% valerenic acid), the purple bottle top, 1-2 caps about an hour before bed. The stink is worth it to sleep.
h. L-Theanine: this stimulates alpha waves, to make you calm. It made me feel snowed. For sleep I'd actually want delta waves. But in many examples, calming is a good way to wind down to sleep.
i. GABA: I have tried 250 - 500 mg 30-60 minutes before bed. If you read about GABA, supposedly it doesn't cross the blood-brain barrier. But if you take too much, it will mellow you out and it made for some morning fog over time. FYI, usually benzos (Xanax, Ativan, etc.) work on enhancing your brain's GABA actions to calm your mind. I had to stop using it because it made me "too mellow" all day and I felt like blah.
j. 5-HTP: a precursor to serotonin. I tried a couple times, woke up with a big headache and fog. Gong...
Good grief. Reading all that could be a sleep inducer...
As you can see, sleep is part mental, part physical, part nutritional, part hormonal, part habitual.
SUMMARY: my favorite helps I am using currently:
1. At least 1 hr. time to wind down at night, dimmer lights, decrease noise. Stretch, breathe, pray.
2. Quiet, dark, cool , undisturbed sleep environment sleeping alone.
3. Supplements: Mg Citrate +/- Valerian cap (or 2 Valerian if racing mind) or else I'll try 1-2 Chamomile caps. If I've stayed up too late over the weekend, I may change to or add MidNite tab, 1/2 - 1 tab.
4. In the morning, get into bright light (to stop melatonin secretion), take Tyrosine 500 mg and Vit.B12 500 mcg, and some coffee or pop.
** NOTE: If you try different things, be sure to keep a log book, with dates; record how you slept, fell asleep, woke up, etc. That way it is easier to remember 'what works for you'. Also - I HIGHLY recommend the 2 sleep books I mentioned above, so you can learn more about how to sleep better. Many apologies for the long post.