My quickie research has found the following useful tips:

Sleep hygiene

Sleep hygiene is one of the components of behavioral therapy for insomnia. Several simple steps can be taken to improve a patient’s sleep quality and quantity. These steps include:

• Sleep as much as you need to feel rested; do not oversleep.
• Exercise regularly at least 20 minutes daily, ideally 4-5 hours before your bedtime.
• Avoid forcing yourself to sleep.
• Keep a regular sleep and awakening schedule.
• Do not drink caffeinated beverages later than the afternoon (tea, coffee, soft drinks etc.) Avoid “night caps,” (alcoholic drinks prior to going to bed).
• Do not smoke, especially in the evening.
• Do not go to bed hungry.
• Adjust the environment in the room (lights, temperature, noise, etc.)
• Do not go to bed with your worries; try to resolve them before going to bed.

Herbal Supplements and Hormones

• Herbal supplements. There are several herbal remedies thought to help sleep. Examples include chamomile, valerian root, kava kava, chamomile, lemon balm, passionflower, lavender, and St. John?s Wort. These remedies have not yet been scientifically proven to work, although many do try them. Note that the effectiveness of herbal supplements has not been evaluated by the Food and Drug Administration. Herbal supplements can have side effects. Check with your healthcare professional if you are trying these, as they may interfere with some prescribed medications. St. John?s Wort, for example, can limit the effectiveness of many prescribed medications such as blood thinners, birth control pills and some anticancer medications.
• Melatonin. Melatonin is a naturally occurring hormone whose levels peak at night. It is triggered by dark and levels remain elevated throughout the night until light decreases it. For this reason, melatonin has been studied for use as a sleep aid. However, most study results have not found it to be beneficial when compared to a sugar pill (placebo). Some positive results have been shown in helping adjustment to jet lag and shift workers who work nights. However, it?s unclear whether simple exposure to light at the right time is more effective, and there is no risk of side effects with light exposure. Long term uses of melatonin are unknown.