A classic aid for getting a good night’s sleep is to warm a combination of turmeric and milk (or a milk substitute) together in a saucepan before going to bed. One way to increase the sleep-inducing effectiveness of this compound is to add a little bit of ginger and some cinnamon. In cases where maximum effectiveness is desired, it is generally believed that black pepper has a substantial impact upon the bioavailability of curcumin (the active ingredient in turmeric) in the bloodstream, although its effectiveness may wear off in a short period of time.
In any case, for the purpose of trying to get to sleep, pepper does seem to give turmeric the kick it needs to really work. It is also best to use the turmeric root itself rather than powdered turmeric. Before turmeric is powdered it is cured, a process which involves first boiling the root and then drying it in a hot oven. As any good cook knows, boiling and then heating tends to reduce the potency of the ingredient being used. Therefore, if possible, use slices of the root itself. Studies have shown that powdered turmeric contains only 3.14% curcumin on average. Turmeric looks quite a bit like ginger in its root (or rhizome) form and can be used in a similar way.
A simple recipe for using turmeric as a soporific is to put about half a teaspoon of turmeric into 2-3 cups of milk along with ginger and cinnamon and a pinch of black pepper or a couple of smashed peppercorns. It should be heated about 10-15 minutes to get the milk infused enough with the turmeric and other spices. The result is usually considered to be a tasty drink. Some people claim that coconut milk is the best non-milk substitute for milk in this case, since it mimics the constitution of blood plasma and can therefore deliver curcumin to the cells more effectively. In either case, using the above ingredients should be sufficient to induce sleep within about 15 minutes.
But finally it may be wondered why turmeric works as a soporific. The answer is that curcumin lowers the blood sugar levels in the body by stimulating the body to store rather than use glucose. When blood sugar levels drop the result is that the body has less energy since the cells are no longer being stimulated by the uptake of glucose. Here it can be seen why it is important not to take high doses (more than three teaspoons per day) as it may create problems associated with hypoglycemia, may lead one to feel “sick to one’s stomach” and may, in the long run, lead to more serious side effects. Few individuals are in danger of taking such a high dosage, however. The amount of turmeric in curry powders is usually well below 3 teaspoons, and even when sprinkling turmeric itself into food preparations, three tablespoons is enough so that few individuals would find the result very appealing. Finally, it should be noted that turmeric may not be suitable for diabetics who are taking medication that lowers their blood sugar level. Taking a large dose of turmeric would very likely induce very low blood sugar levels which might lead to further complications.
As in many other things, moderation is the key. Taken daily in moderate doses, turmeric can really boost one’s health. It is useful against arthritis, promotes good cholesterol and lowers bad cholesterol levels, helps fight or prevent cancer, and supports good digestive functioning. 
1. See Planta Med. 1998 May;64(4):353-6. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS (http://www.ncbi.nlm.nih.gov/pubmed/9619120). This study promised good results for the absorption of curcumin when then taken with piperine (black pepper extract) but has been criticised for being poorly carried out. More promising methods of increasing curcumin absorption have involved breaking it up into nanoparticles and other methods usually out of reach for the sleep deprived. In any case black pepper is a traditional way to increase the effectiveness of turmeric.
2. The webpage http://kaubic.in/spicesdatabase/Turmeric/processing.htm is an excellent resource on turmeric processing.
3. See naturalnews.com http://www.naturalnews.com/043175_blood_sugar_levels_medicinal_spices_diabetes.html
4. See University of Maryland medical center’s website at http://umm.edu/health/medical/altmed/herb/turmeric, University of Maryland medical center, power-of-turmeric.com at http://www.power-of-turmeric.com/curcumin-and-diabetes.html, and Livestrong: http://www.livestrong.com/article/475347-natural-spices-to-lower-blood-sugar-levels/ for further information.
5. See Epicurean Digest at http://epicureandigest.com/dosage-and-method-turmeric/
6. See the World’s healthiest foods article on turmeric: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=78