Update January 2010: I am withdrawing my recommendation of this due to the presence of ingredients such as behentrimonium chloride. My original review is below.

It is too soon to know if I will experience results similar to those of the participants in an independent trial for Kronos Phyx Overnight Repair Masque. After four weeks hair strength and elasticity was improved by a whopping 96% and volume by a more modest, but nevertheless welcome, 26%. I have only used this hair mask twice, but so far I am prepared to be convinced that Phyx is worth its steep $105 price tag.

Kronos is one of the few brands to have an anti-aging hair care line. The Phyx mask is the cream of the crop and it is packed with antioxidants, vitamins and botanicals that have a proven track record. After two uses, I can report that it certainly makes your hair look thicker and stronger. I would recommend this for anyone who has thinning, brittle hair - and is feeling flush.

One of the most convincing ingredients is hexapeptide-11. Studies have shown that this can signal genes responsible for collagen production and it can upregulate the androgen receptor in the way that testosterone can, suggesting that it can help with hair regrowth. Then there is phytosphingosine, a lipid that is the precurser to ceramide.

Pearl powder is another intriguing ingredient for a hair care product. The thing that makes pearls pearly is called conchilion. As documented in the Journal of Cell Biology in 2006, conchilion acts like the protein keratin (which is found in skin, bones and hair).

There are a couple of different types of green tea, plus rice bran to bring antioxidant power. Lycium chinensis is a good source of betaine, an amino acid. Another Chinese plant is cudrania tricuspidata, a kind of mulberry tree that is good for stimulating the circulation. Meanwhile, researchers in Japan have found prunus mume to be an effective scavenger of free radicals. Crithmum maritimum is sea fennel and French researchers have pronounced it a "valuable source of antioxidants, particularly chlorogenic acid". Over in Korea, researchers have found antioxidants in the seeds of rubus coreanus (wild strawberry).

The Kronos line also boasts something called T-Sphere Technology. Leaving aside connotations of the Batman, it is supposed to help ingredients penetrate. I hope that one day, the Kronos formulator puts as much effort into finding safe alternatives to some of the silicones and preservatives in this product. I am also not sure how I feel about fullerenes, the powerful scavenger of free radicals but also regarded as controversial because some studies suggest it is cytotoxic. The data, however, is patchy. In the end, Kronos is full of many more good things than bad.

Finally, I was a little trepidatious about the whole idea of going to bed with gunk on my hair and waking up with stained and greasy pillow slips. My fears were unfounded; the thick cream dries quickly and the worst thing to be said is that locks have that lovely limp, unwashed look (not for romantic evenings).

Ingredients in Kronos Phyx

Water (Aqua), Behentrimonium Chloride, Cyclopentasiloxane, Dimethicone, Cetearyl Alcohol, Cetrimonium Chloride, Polyquaternium-37, Phenylpropyldimethylsiloxysilicate, Dimethiconol, Hydrolyzed Lupine Protein, Glycerin, Astrocaryum Murumuru Seed Butter, Orbignya Speciosa Kernel Oil, Oryzanol, Tocopherols, Tocotrienols, Citrus Medica Limonum (Lemon) Fruit Extract, Saccharum Officinarum (Sugar Cane) Extract, Betaine, South Sea Pearl Powder Extract, Brazilian Coral Powder Extract, Camellia Sinensis Leaf Extract, Hexapeptide-11, Pyrus Malus (Apple) Fruit Extract, Acetyl Hexapeptide-3, Cucumis Sativus (Cucumber) Fruit Extract, Cudrania Tricuspidata (Mulberry) Bark Extract, Glyceryl Polymethacrylate, Glycyrrhiza Glabra (Licorice) Root Extract, Lycium Chinensis (Chinese Matrimony Vine) Fruit Extract, Oryza Sativa (Rice) Bran Extract, Prunus Mume (Ume) Fruit Extract, Pyrus Communis (Pear) Fruit Extract, Rubus Coreanus (Wild Strawberry) Fruit Extract, Camellia Sinensis (Uuron Cha Ekisu) Leaf Extract, Crithmum Maritimum Extract, Hydrogenated Vegetable Oil, Fullerenes, Hydrogenated Lecithin, Phytosphingosine, Sodium Hyaluronate, Tocopheryl Acetate, Urea, PPG-1 Trideceth-6, Propylene Glycol Dibenzoate, Propylene Glycol Dicaprylate/Dicaprate, Butylene Glycol, Laureth-23, Laureth-4, Citric Acid, Caprylic/Capric Triglyceride, Cetyl Alcohol, Propylene Glycol, Steareth-2, Steareth-21, Stearic Acid, Carbomer, PEG-30 Dipolyhydroxystearate, Fragrance (Parfum), BHT, Disodium EDTA, Triethanolamine, Isohexadecane, Hexylene Glycol, Ethylhexylglycerin, Phenoxyethanol, Limonene, Linalool.