400-mg capsule of L-ornithine improves sleep
If, every evening before going to sleep, you take a capsule containing 400 mg L-ornithine, the quality of your sleep will gradually improve. You'll fall asleep faster, sleep more deeply and for longer, and you'll feel better during the day, write researchers at the Japanese Kirin Company in Nutrition Journal.
Ornithine, sleep and stress

Kirin is looking for applications for ornithine. This search has been prompted by animal studies in which orally administered L-ornithine had an anxiety reducing effect on mice subjected to stressful situations as a result of its activity in the brain. [Nutr Neurosci. 2011 Nov;14(6):243-8.] What exactly L-ornithine does there is not known. What is known is that it does not inhibit the synthesis of neurotransmitters such as dopamine. [Neurosci Lett. 2012 Jan 11;506(2):287-91.] L-Ornithine supplementation does inhibit the synthesis of the stress hormone cortisol in stressful situations.Study
In this study the researchers gave two dozen healthy subjects aged 30-60, who had complained in the past of mild work stress and moderate fatigue, a capsule containing 500 mg L-ornithine HCl every day for eight weeks. The amount of L-ornithine in each capsule was 400 mg. The subjects took the capsule before going to bed. A control group took a placebo.

The L-ornithine supplementation [black circles] lowered the cortisol level a little, but had no effect on DHEA synthesis. The cortisolHEA ratio improved significantly as a result of supplementation.

During the daytime the subjects in the ornithine group felt less hostile and angry. [#1]

The subjects that took ornithine fell asleep faster and slept more deeply. They scored these aspects of their sleep higher than the subjects in the placebo group did. [#2] In addition, the subjects in the ornithine group slept for longer. [#3]
"Our study suggested that L-ornithine has a positive effect on stress and sleep in healthy workers", the Japanese wrote. "L-ornithine might be beneficial for people who live a stressful life."

Nutr J. 2014 Jun 3;13:53.