Study on Melatonin as a Treatment for Delayed Circadian Rhythms

Introduction to Melatonin and Its Role in Sleep

Recent research has investigated the effectiveness of melatonin as a treatment for insomnia in individuals with delayed circadian rhythms. Over-the-counter melatonin supplements are commonly used to aid with insomnia. Melatonin, a hormone produced by the pineal gland in the brain, plays a crucial role in regulating sleep. Its production is inhibited by light during the day and increases at night, promoting sleepiness. Given its significant role in sleep cycles, researchers aimed to evaluate its efficacy for a specific sleep disorder known as delayed sleep-wake phase disorder (DSWPD).

Understanding Delayed Circadian Rhythms

Individuals with DSWPD experience challenges in initiating sleep, a symptom that overlaps with sleep-onset insomnia. However, these two conditions are distinct. While those with sleep-onset insomnia have a normal circadian rhythm but struggle to fall asleep, individuals with DSWPD have a delayed circadian rhythm, disrupting their daily activities and potentially impacting mental health, work performance, and social interactions.

Research Overview

A recent study published in PLOS Medicine explored the use of melatonin specifically for treating insomnia in individuals with DSWPD. Conducted at Monash University, the Woolcock Institute of Medical Research, and Flinders University in Australia, the study involved participants who completed online questionnaires to assess their likelihood of having DSWPD, with diagnoses confirmed by a physician.

Participant Criteria and Study Design

To qualify for the study, participants had to be aged between 16-65 years, with a body mass index ranging from 18 to 35 kg/m². Exclusion criteria included night shift work, excessive caffeine or alcohol consumption, drug use, smoking, and psychiatric disorders, apart from depression. Participants also needed to engage in daytime activities at least five days a week and could not have traveled across more than two time zones in the two months prior to the study.

Participants were randomly assigned to receive either a placebo (lactose and cellulose) or melatonin. Each participant was provided with 28 capsules to take one hour before their desired bedtime, at least five days a week for a month. They were required to document their daily activities and answer questions regarding sleep disturbances, focus, irritability, and daytime sleepiness. Compliance was monitored through wrist monitors and the return of unused medication.

Findings on Melatonin’s Efficacy

Both groups utilized their assigned treatment approximately 21.1 times over four weeks, with 63.3% adhering to the regimen of taking their designated pill five days or more for three weeks. On average, there was a two-hour difference between participants’ usual sleep onset and their desired bedtime.

The study revealed that participants receiving melatonin fell asleep 34 minutes earlier compared to their baseline measures. Additionally, the quality of sleep during the initial third of their time in bed showed improvement. The melatonin group experienced reductions in sleep disturbances, sleepiness, irritability, and daytime focus issues, along with a decrease in insomnia severity. Side effects were similar across both groups, including daytime sleepiness and light-headedness.

Regulatory Considerations and Conclusion

It is important to note that melatonin regulations vary significantly across different countries, which may impact access to the specific doses and quality of melatonin used in the study. Moreover, the study’s duration was relatively short, leaving the long-term effects of melatonin on insomnia treatment uncertain. Nevertheless, the findings suggest that melatonin may serve as a viable short-term treatment option for individuals with delayed circadian rhythms.

References

Sletten, T.L., Magee, M., Murray, J.M., Gordon, C.J., Lovato, N., Kennaway, D.J., … Rajaratnam, S.M. (2018). Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder: A double-blind, randomised clinical trial. PLOS Medicine. https://doi.org/10.1371/journal.pmed.1002587

Nesbitt, A.D. (2017). Delayed sleep-wake phase disorder. The Journal of Thoracic Disease, 10(Suppl 1), S103-S111. http://dx.doi.org/10.21037/jtd.2018.01.11