I have recently tried midnite (sp)? which has a small amt of melatonin and herbal extracts mentioned here. I tried this because the herbals alone did not do much, but this seems to work. note I tried these to keep a desired schedule rather than to address not being able to sleep at all. Both are available at the drug store. You could also try a soft sleep mask which can help darken out stray light.

If you think there is not an underlying stressor or physical issue you might try this. If there is or could be, please visit your doctor.