Frequently Asked Questions
Question: Should I control light, exercise, meal times, posture, drug intake, temperature, nutrients, alcohol, caffeine, in subjects giving blood, saliva or urine for melatonin measurement?
Answer: Yes depending on the information you require, but the most important are light (which suppresses melatonin) and drugs (many drugs change melatonin production and/or metabolism).
Question: How do I collect blood for melatonin measurement?
Answer: The best method is by indwelling cannula with samples transferred to heparinised tubes. Centrifuge within 15 minutes, store plasma at -20°C. Haemolysed plasma and plasma left in plastic pipettes for more than 2-3 minutes may give fasely elevated melatonin levels.
Question: How do I collect saliva for melatonin measurement?
Answer: All saliva assays require at least 1 ml saliva. The best method is to ask subjects to spit into polypropylene tubes. Do not stimulate saliva production. Do not collect more frequently than every 20 minutes as the relationship with plasma melatonin may be changed. Subjects should not eat within 30 minutes of sampling and must wash out their mouths with tap water before spitting. Some nutrients interfere with assay in saliva. Saliva left in plastic pipettes for more than 2-3 minutes may give falsely elevated melatonin levels. Store at -20°C.
Salivettes from Sarstedt Ltd can be used to collect saliva samples. The same general principles of saliva collection apply. The salivettes used should be with an untreated cotton plug. It is important that the cotton plug is chewed for 1-2 minutes to ensure it is fully saturated with saliva. The volume collected cannot be determined until the salivette has been centirifuged for 15 minutes at 3000 rpm to harvest the saliva. Samples should be stored at -20°C. Use of salivettes may give falsely elevated melatonin levels and standards should be run through salivettes to correct for this.
Question: How do I collect urine for 6-sulphatoxymelatonin measurement?
Answer: Ask subjects to collect all urine passed over a preset period into a standard urine bottle. Measure and record the volume, keep circa 5 millilitres at -20°C. No preservative is required, 6-sulphatoxymelatonin is stable in urine for one day at room temperature, 2 days at 4°C and for at least 2 years at -20°C. Never wash urine bottles with bleach or other oxidant. Urine should be collected at least 3-4 hourly (longer during sleep period) for at least 24 h, preferably for 48 h or longer.
Question: What does Stockgrand charge for performing the measurement of melatonin and or 6-sulphatoxymelatonin?
Answer: Ask us to give a firm quotation - we are very reasonable. There is discount for bulk orders.
Question: What does melatonin do?
Answer: It is a time cue for the organisation of (especially) seasonal and circadian rhythms. It indicates darkness to the body and reinforces physiological processes that occur at night e.g. sleep in humans.
Question: What diseases are associated with abnormal melatonin?
Answer: See 'Melatonin and the Mamalian Pineal Gland', author J.Arendt, Publisher Chapman Hall, London, 1995 for an extensive discussion. A lack of melatonin, or decreased concentrations in body fluids, is hypothesised to increase the risk of cancer especially breast cancer in shift workers. However a causal connection has yet to be established.
Question: Where can I obtain melatonin?
Answer: There is at least one licensed preparation available in the UK with a doctors prescription. The manufacturer is Penn Pharmaceuticals, Unit 23/24, Tafarnaubach Industrial Estate, Tredegar, Gwent, NP2 3AA, UK, Fax +1495 711225 Tel +1495 711711. In some countries it is available without a prescription.
Question: Is melatonin safe to take?
Answer: No-one knows for sure, especially in the long term.