Melatonin and Autism Ranking:

Status Research

There are a number of limitations to all of the research studies published to date. For example

• Three of the studies were retrospective case-series, with no form of experimental control, and two of these had fewer than ten autistic participants.
• Five of the studies used single-case designs (open trials) and two of these had fewer than ten autistic participants.
• Four of the randomised controlled trials had fewer than 20 autistic participants.  One these (Garstang and Wallis, 2006) had a high level of drop outs (4 out of eleven participants).  One of the randomised controlled trials (Cortesi et al, 2012) was unbllnded.
• Gringras et al (2011) reported a number of limitations to their study including “…. the relatively high number of participants who were either unable to tolerate actigraphy [portable measuring device attached to the child] or in whom actigraphy equipment failed.”  They also defined the minimum clinically important difference of sleep time at 60 minutes, when in fact most of the participants increased the amount of sleep by 22.4 minutes, which might be significant for those individuals.
• Cortesi et al  (2012) reported a number of limitations to their study including the limited treatment period (12 weeks); the fact that they did not measure melatonin salivary and plasma level or its urinary metabolite before and during the treatment; the fact that some people were excluded (for example, if they had serious medical conditions); parents of participants had to comply with the treatment regimen; the fact that some people with conditions which could have influenced the results (such as obstructive sleep apnoea syndrome) may not have been excluded.
• None of the studies appeared to involve autistic people in the design, development and evaluation of those studies

For a comprehensive list of potential flaws in research studies, please see ‘Why some autism research studies are flawed’.

Updated

16 Jun 2022

Last Review

01 Nov 2017

Next Review

01 Apr 2024