To the casual observer, it may appear that some months ago I started to blog on sleep, wrote a few posts… and then simply disappeared from the blogosphere. Unfortunately, April was a month of over-commitment on my part (I’m really good at that). But, I’m back…
During the last few days, my Google reader has been filled with reports of a controversial new brownie (‘Lazy Cakes’) available for sale in the United States. This latest edition adds to a range of baked goods and/or dietary supplements aimed to promote relaxation and therefore supposedly, sleep.
Sold at supermarkets, and department and convenience stores, Lazy Cakes contain ingredients the manufacturers believe promote relaxation, such as valerian root, rose hips and melatonin. Although not explicitly cited on the Lazy Cakes website, web commentary has suggested that these products may be used to promote sleep. Certainly, a New York Times article cites individuals with insomnia who have tried Lazy Cakes. Much of the web discussion at present has centred on the use of melatonin in these brownies and in particularly, the reasonably high dose of 8mg melatonin per brownie.
There is considerable concern about taking melatonin as a dietary supplement. Melatonin is a neurohormone that interacts with a number of systems in the body, of which only one is the circadian (body clock) system. It also has a significant role in the control of our reproductive function, thermoregulation, thyroid function, carbohydrate and lipid metabolism, urine output, immune function… the list goes on.
Many people associate melatonin with a sleep-promoting hormone because it is secreted at night (coincidentally when humans sleep) and suppressed by light during the day. In fact, melatonin is secreted at night regardless of whether we are diurnal (active during the day) or nocturnal (active at night). When it comes to sleep/wake information, melatonin’s main role is to tell us what time of day it is. Melatonin also changes seasonally in all mammals (including humans) so it can also tell mammals what time of year it is, which is important for reproduction and hibernation.
Many studies have considered the influence of melatonin on our sleep timing and quality. In humans;
- Melatonin’s main action is in its ability to shift the timing of our sleep by changing the timing of our body clock. This means that taken at the wrong time of the day, melatonin may shift the timing of your sleep to an undesirable time. Timing instructions do not come on the packets/bottles of melatonin-containing products. Would you know exactly when you should be administering melatonin to optimise your sleep timing?
- Melatonin has no effect on sleep quantity or quality when used as a sleep aid.
- Timed appropriately, melatonin can shorten the time it takes you to fall asleep but in healthy adults, this effect is usually incredibly small (something like 4 minutes on average; statistically significant but not clinically significant). It does seem to be more effective at reducing the time it takes to fall asleep in those with insomnia, but it still does not change sleep quantity or quality in this group.
- Acute side effects include, commonly, headache and taken during the active day, sleepiness and fatigue.
- We do not know the long-term risks associated with frequent administration or inappropriate timing of melatonin. At present, the greatest concern lies with its effect on our reproductive function, including reproductive cancers.
To the general public, melatonin is usually promoted as a product for those who are having trouble sleeping, including those with insomnia. As someone who is not an advocate for pharmacologic treatment for chronic insomnia, if it were me, would I regularly take dietary supplements containing melatonin to improve my sleep? Not on your life.