This is probably not a good idea.

The National Institutes of Health's Medline Plus listing on valerian states that there's "not enough scientific evidence to recommend the use of valerian in children."

Before turning to any kind of sleep aid in a child - have you talked to her pediatrician, teachers and any counselors at school to find out what may be going on in her life that makes sleep difficult? There may be medical or social reasons for the problem that can be addressed.

Here's a discussion on use of valerian in this forum, in which a number of participants warn against prolonged regular use of this herb, to prevent people from becoming dependent on it and/or having it lose effectiveness through long-term use.

Agreed, I would do more digging to find the source of the problem before giving my child any sleep aids, herbal or non. The potential for becoming dependent on them is high and could set your child up for sleep problems in the future. I would try relaxation techniques first, eat smaller meals earlier in the evening, do a slow-down of the day earlier, no stimulation like television in the room, darken the room and get a soothing cd and then starting at the top of the head and working down to the toes tighten every muscle, then relaxing it.

Some good suggestions there from silversword. Sleep aids of any kind should be a last resort, especially for a child this age.

Look at how much activity does she get? Does she most of her physical activity just before bedtime? If she does she may be too hyped to sleep. What is her bedtime? Is it too early for her? These are questions you might check on before taking her to doctor.

A question I would also want to know is what does she do during the 2-3 hours that she can't fall asleep. Text her friends, lay there, or what?

Hi thpinky,
Core body temperature cycle normally shifts in adolescence. A drop in this core temperature is correlated to inducing sleep & subsequent rise before awakening is the counterpart cycle. In other words no dropping off to sleep naturally without this core down shift.
(There seems to be a mini-cycle around mid-day; which many assume is why they are sleepy after lunch.)
In teenagers the core body temperature normally rises a little later in the morning. This is part of why they are notorious sleepy heads when supposed to get up for school; ditto for many university students.
Whether this is driven by melatonin "sleep" hormone secretion, or is the modulator of the melatonin cycle, is debatable. What is certain is that the "stress" hormone cortisol that keeps kids keyed up has an antagonistic relationship with the "sleep" hormone. (In other words: got cortisol circulating, then don't get to sleep .)
So, what to do ....
Strong light entering through the eyes act on the brain & this gives an easy way to alter the dynamics involved in sleep patterns. Therapeutic technique involves controlling what time get first & last exposures to natural light in order to shift the pattern of sleep.
(Good sleep habits integrate well into strong light manipulations.)
You should be able to find out more online about this safe approach; search for "strong light" & "light box".

Totally normal for 14 year old sleep cycle to shift & to do so abruptly, throwing off mom/dad's sense of what is "normal". They will self-adjust. Turn off the Xbox/wii/tv/radio/cell phones & tell them if they want to stay up, go ahead-- just can't do it with sound or light. If they fall asleep in school, they bear the consequences. Repeat: They will self-adjust.

Re hormone rages: good diet, good exercise, good manners, good attitude, good expectations. They will self-adjust.

If you want to get herbal: catnip, chamomile, rose buds, hyssop & hibiscus make very calming teas alone or together. Best use is to help deal with every day stress than to expect a cuppa tea to put you to sleep. Valerian helps release myofacial tissue, so is a physical relaxer, excellent for girls during menstruation. White willow will have similar results & is NOT sufficiently strong to cause excess bleeding. 14 year olds of normal body size can take an adult dose in tea form with no concerns as long as there is no indication of sensitivity.

good diet, good exercise, good manners, good attitude, good expectations.
Good advice