Melatonin – what do we know?

Melatonin has often been mentioned in my posts, without a deep dive into it.

Melatonin, also known as N-acetyl-5-methoxy tryptamine,[1] is a hormone that is produced by the pineal gland in animals and regulates sleep and wakefulness” [Wikipedia]

The more likely cause of sleep disorders with CFS/FM/IBS is hypoxia (low oxygen) which is known to cause severe sleep problems. Melatonin can help with that, but other oxygen delivery items should be considered too.

On the flip side, there some some bacteria that are associated with a lack of sleep: Partial Sleep Deprivation. On DataPunk.Net we read:



In other words, it contributes to a shift of the firmicutes/bacteroidetes ratio.

  • ” in particular through [Melatonin] ability to decrease the Firmicutes-to-Bacteroidetes ratio and increase the abundance of mucin-degrading bacteria Akkermansia, which is associated with healthy mucosa. ” [2017] – Checking Akkermansia levels first (most are low, but a few are high).


Bottom Line

If someone has a high firmicutes/bacteroidetes ratio (i.e.  firmicutes > 1.2x and /or bacteroidetes < .8x) then melatonin is a reasonable supplement, especially if there is overgrowth of  Coriobacteriaceae or Erysipelotrichaceae.  This applies to a subset of CFS patients.



On the Family Level


The dosage is unclear. The literature reports: “0.1 mg to 50 mg/kg “, so for 100 lb individual:

  • 4.5 mg/day to
  • 2 gram/day

“For trouble falling asleep: 0.3 to 5 mg of melatonin daily for up to 9 months has been used. For sleeping problems in people with sleep-wake cycle disturbances: 2 mg to 12 mg taken at bedtime for up to 4 weeks has been used.” [WebMD]

Poison Control reports:


“307 articles were elicited and 9 were related to Melatonin adverse effects. The range of MLT dose involved in the adverse reactions oscillated between 1 mg and 36 mg. The adverse reactions were: one patient with autoimmune hepatitis, one case of confusion due to MLT overdose, one case of optic neuropathy, four subjects with fragmented sleep, one psychotic episode, one case of nistagmus, four cases of seizures, one case of headache and two cases of skin eruptions.” [2001]

As always, consult with your medical professional before starting or altering your supplements.