I'll take a smoothie and a siesta over Ambien anytime

If you've ever dieted, and you have trouble sleeping...there may be a reason. Keep in mind, this study was done on rainbow trout, but there is still a message in it for humans. Three groups of trout were studied with regard to their melatonin (sleep hormone/antioxidant) levels and cortisol (stress hormone) levels. The three groups were defined as fed fish, fish that were fasted for 7 days, and fish that were fasted for 7 days then refed for 5 days.

Melatonin levels were disrupted in fasted fish. If you were human, this would likely mean if you were on a strict fasting/dieting protocol, you were probably having trouble sleeping as well.

Interestingly, nighttime serotonin levels were higher in these fasted fish. Melatonin is made from serotonin, so I would presume that what the body tries to do when you're not eating well is to keep you alert and thinking about getting some food. It does that by hanging on to serotonin and preventing its conversion into melatonin. That's a survival mechanism.

So if you're dieting and you're awake at night with cravings? That's a normal response. Don't obsess about what's wrong with you, don't surf the Internet looking for what to do about your cravings. In this kind of situation, you're thinking about food because you need it. Get some.

As far as cortisol, dieting reduced levels and they stayed low after refeeding. You could argue that this is a benefit of dieting...except for the fact that if you're cutting yourself short on melatonin, you're aging yourself more quickly than you should. There are plenyy of ways to reduce melatonin levels without dieting that don't cut your life short on the back end.

By the way, since I write so much about sleep I thought I should mention...I love naps. The long afternoon kind where my cats curl up with me, and I wake up with a little bit of drool on my pillow. I don't feel guilty at all. I completely buy into the idea of "beauty sleep"--sooooo much cheaper than all those anti-aging potions on the infomercials!

Ceinos RM, Polakof S, Illamola AR, Soengas JL, Míguez JM. Food deprivation and refeeding effects on pineal indoles metabolism and melatonin synthesis in the rainbow trout Oncorhynchus mykiss. Gen Comp Endocrinol. 2008 Apr;156(2):410-7. Epub 2008 Jan 8.