VALERIAN

What is it? Valerian officinalis is a perennial herb, with small pink, white or purple flowers (pictured). Extracts of the roots are used medicinally.

Does it work? A 2006 review examined 16 trials with more than 1,000 patients and concluded that it might improve sleep. Further research is needed to support these findings. Valerian does not appear to work as a single dose; the benefits are most apparent after a few days and it appears to have minimal side-effects. Animal research suggests that it mimics a chemical that readies the brain for sleep. Recent studies suggest that it’s more effective when combined with hop extract.

LAVENDER OIL ON YOUR PILLOW

What is it? An oil distilled by passing steam through large quantities of mature lavender (Lavandula augustifolia) flower heads.

Does it work? A 2005 pilot study of ten volunteers suggested that it might. A larger study last year on 43 student nurses found that it eased anxiety and reduced insomnia.

LEMON BALM SUPPLEMENTS

What is it? The herb Melissa officinalis is used in cooking and as a remedy for anxiety.

Does it work? A 2005 review of herbal insomnia remedies found no evidence that lemon balm is more effective than a placebo. But a 2003 study suggested that high doses of lemon balm extract increased calmness and reduced anxiety.

HOPS SUPPLEMENTS

What is it? Humulus lupulus is a tall climbing plant (pictured), the flowers of which are used to flavour beer and as traditional medicines.

Does it work? The evidence for hops alone is scarce, but there is growing evidence that it can be effective when combined with valerian. A trial this year of 30 patients found that valerian extract alone was no better than a placebo but a combination of hops and valerian did improve insomniacs’ sleep.

CAMOMILE

What is it? There are many species but the most commonly used are German and common camomile.

Does it work? There are no good trials of camomile tea or tincture on insomnia. It is used as an aromatherapy oil and there is some evidence that aromatherapy can ease insomnia.

PASSIONFLOWER SUPPLEMENTS

What is it? There are about 500 members of the Passiflora species, and extracts from only a small number are used medicinally.

Does it work? Studies on Passiflora incarnata have shown that it reduces anxiety in laboratory mice. There are no clinical trials to confirm that it might be effective in human beings. Toby Murcott is a former BBC science correspondent

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