A very well known but consistently noticable side effects of aromatase inhibition is joint stiffness. Everyone from men who want to lower estrogen to women who are treating breast cancer have complained of this side effect and it may be that melatonin is involved in this process. Why? Well apparently this reduction of estrogen (by inhibiting an enzyme that converts hormones into estrogen) affects our pineal gland's ability to suppress melatonin (the pineal gland is responsible for melatonin release and suppression) during the day. The take home message? Get more sunlight during the day if you're using things to suppress estrogen. This doesn't mean you need to get a tan but it does mean getting away from the computer for a minute and enjoying more time outside, provided it's not dark and rainy... Or you can do what they did in the study
If worn first thing in the morning, the cap sharply curtailed the duration of morning stiffness. If worn for a sufficient number of hours during the day, the cap suppressed symptoms the next morning, just as sunlight did. Because of evidence for melatonin's oncostatic properties, this hypothesis potentially has implications beyond decreasing the number of patients that discontinue AIs. It may be that some portion of the survival benefit of AIs is due to their indirect effect on melatonin, not just their direct effect on estrogen.
Beyond that it is simply more information helping us to better understand just how intricately all hormones and peptides in the body are interlaced in their physiological effects. As well it also might be giving us further information about how melatonin can actually be a powerful anti-cancer agent. There are some that hypothesize melatonin given in large amounts can suppress cancer in the body. It may very well be that aromatase inhibiting drugs used to lower estrogen in women may actually provide an indirect anti-cancer effect by increasing melatonin production all day.
