Both
chronic pain and
sleep disorders are associated with a reduction in the quality of life. They can be both a cause and a consequence of each other, and should therefore be simultaneously treated. However, optimal treatments for
chronic pain-related
sleep disorders are not well established. Here, we aimed to investigate the effects of
suvorexant, a novel sleep
drug, and
mirtazapine, a noradrenergic and specific serotonergic
antidepressant, on
pain-related changes in sleep parameters in a preclinical
chronic pain mice model, by partial sciatic nerve
ligation. We evaluated the quantity, duration, and depth of sleep by analyzing the electroencephalogram and voluntary activity by counting the number of wheel rotations to determine various symptoms of
sleep disorders, including reduced total sleep time, fragmentation, low quality, and impaired activity in the daytime.
Suvorexant and
mirtazapine normalized the reduction in sleep time and fragmented sleep, further regaining the sleep depth at sleep onset in the
chronic pain state in nerve-ligated mice.
Mirtazapine also increased the percentage of rapid eye movement sleep in mice.
Suvorexant decreased voluntary activity, which was prolonged after administration; however,
mirtazapine did not decrease it. Although the effects of
suvorexant and
mirtazapine on sleep and activity are different, both
suvorexant and
mirtazapine could be potential therapeutic agents for
chronic pain-related
sleep disorders.