5-Hydroxytryptophan (5-HTP) is an amino acid closely related to serotonin and melatonin – two chemicals that regulate sleep. This raises the possibility of using 5-HTP to treat sleep disorders such as insomnia. In this post we take a look at the effects of 5-HTP as well as related supplements that help give a better night’s sleep.
- 5-HTP is a precursor to serotonin and melatonin
- Imbalances of serotonin and melatonin are linked with sleep disorders such as insomnia
- Studies suggest 5-HTP supplementation helps restore an optimal balance of these chemicals
- 5-HTP supplementation has been shown to increase REM sleep
- How effective 5-HTP is is likely to depend on the cause of sleep disorders
What is 5-HTP?
5-Hydroxytryptophan (5-HTP) is an amino acid found in small quantities in the typical diet.
Most 5-HTP is produced from another amino acid, tryptophan. Tryptophan is found in most high-protein foods such as eggs, meat, fish and poultry.
When taken orally, 5-HTP is able to cross the blood-brain barrier.
5-HTP is a particularly crucial amino acid as it’s the chemical precursor to the neurotransmitter serotonin (5-HT) and the hormone melatonin – both of which are critical for normal sleep cycles.
Serotonin is typically associated with psychological well-being and relaxation. Low serotonin is linked with mood disorders such as depression and anxiety. And there is evidence that 5-HTP supplementation can help with both these issues.
But serotonin also appears to be implicated in sleep1,2,3 – though the exact relationship is unclear. This may be because serotonin is used to produce melatonin – the hormone that regulates sleep and wakefulness. And studies have shown 5-HTP supplementation increases melatonin levels.
All this raises the possibility that 5-HTP may help with sleep problems such as insomnia (difficulty getting to sleep and/or staying asleep). But what does the evidence say?
5-HTP for better sleep (studies)
Various studies have looked at the links between 5-HTP, serotonin, melatonin, and sleep – with mostly positive results.
But it’s not as simple as more 5-HTP = more sleep.
Studies in mice, for example, have found 5-HTP to both increase and decrease sleep onset depending on dose and time of administration. When administered at night (dark period), 5-HTP increased non-REM sleep in the mice. However, the same dose during daytime (light period) actually increased wakefulness. Similar observations have been made in rat studies1,2.
It’s a similarly complex situation with people.
In humans, insomnia is correlated with low serotonin levels1,2. 5-HTP is converted to serotonin so should increase levels of this hormone. In theory, this should help insomniacs get to sleep – especially if low serotonin is the cause of insomnia:
“In the CNS, serotonin levels have been implicated in the regulation of sleep, depression, anxiety, […] Therapeutic administration of 5-HTP has been shown to be effective in treating a wide variety of conditions, including depression, […] and insomnia.”
And studies in normal subjects (i.e. people without sleep disorders) have found 5-HTP supplementation to increase REM sleep from 5% to 53%:
“The effects on sleep of increasing brain serotonin with 5-hydroxytryptophan (5-HTP), the immediate precursor of serotonin, were studied on twelve normal subjects. In each subject, rapid eye movement (REM) sleep increased from 5 to 53% of placebo baseline. The total rapid eye movement activity also increased. Non-REM sleep decreased slightly, apparently compensating for the increased amount of REM sleep.”
Many supplements have a synergistic effect with 5-HTP that work to improve sleep quality and duration. These include melatonin and GABA.
While not necessarily better or worse, the effects of melatonin are far more clear-cut than 5-HTP and serotonin.
Not only that, at least one meta-analysis (study of studies) has confirmed these sleep-promoting effects:
“This meta-analysis demonstrates that melatonin decreases sleep onset latency, increases total sleep time and improves overall sleep quality. The effects of melatonin on sleep are modest but do not appear to dissipate with continued melatonin use.”
As the main inhibitory neurotransmitter, GABA is responsible for reducing excitability throughout the nervous system. Unsurprisingly, low levels of GABA make it difficult to fall asleep. But supplementation with GABA can counteract this effect and has been demonstrated to help people fall asleep quicker1.
What’s more, GABA appears to have a synergistic effect on sleep regulation when used in conjunction with 5-HTP.
This study tested the effects of a GABA/5-HTP supplement on a small sample of patients with sleep disorders. Neither the subjects nor the researchers knew which patients had received the GABA/5-HTP supplement and which had received the placebo. The researchers observed that:
“An amino acid preparation containing both GABA and 5-hydroxytryptophan reduced time to fall asleep, decreased sleep latency, increased the duration of sleep, and improved quality of sleep.“
– A randomized, placebo-controlled trial of an amino acid preparation on timing and quality of sleep. PMID: 19417589
Similar effects have been reported in at least one other study1.
Causes of insomnia
Insomnia is the most common sleep disorder worldwide with around 30% of adults reporting one or more symptom1.
It’s more common among women than men and the likelihood of developing insomnia increases with age.
Environmental and lifestyle factors – caffeine and alcohol consumption, night shift work, noise and distractions, etc. – may cause difficulty sleeping and should be the first port of call for improving sleep quality and duration.
Insomnia may also be a symptom of underlying health issues such as anxiety and depression.
5-HTP for sleep: summary
The relationship between 5-HTP and sleep is not a simple one.
5-HTP is known to affect serotonin levels – but the exact relationship between serotonin and sleep is not clear.
And with many potential causes of insomnia it seems unlikely that 5-HTP is a one-size-fits-all solution to sleep disorders.
But the available evidence suggests 5-HTP supplementation may encourage deeper sleep with fewer interruptions. 5-HTP is also more likely to be effective for sleep disorders that are a symptom of serotonin-related mental health problems such as anxiety or depression.
For other causes of sleep disruption, 5-HTP may have synergistic effects when used in conjunction with other sleep-promoting supplements such as GABA and melatonin.