Mechanisms which connect anxiety with insomnia
Anxiety, stress and excitement can cause us to stay awake or have restless sleep – and at some point in our lives we have all experienced this.
But the mechanisms which take place in our brain have been unclear so far.
Researchers from the Sleep Institute in Japan recently discovered the neurons which play an important role in linking emotions to sleep and discovering options for drug therapy which can be useful in anxiety and sleep disorders.
The study involved investigating sleep in mice.
Part of the amygdala, known as the bed nucleus of the stria terminalis (BNST) plays a key role in stress response, fear and anxiety.
Stressful or emotionally inducing situations such as encountering predators, adapting to a new environment or expecting a reward require animals to shift to vigilante state which involves altering their physiological conditions through changes in their automatic and endocrine functions.
Part of the amygdala, known as the bed nucleus of the stria terminalis (BNST) plays a key role in stress response, fear and anxiety. Through projections in various regions of the brain – including relay nuclei of the autonomic nervous system, hypothalamic regions and the central nucleus of the amygdala, the BNST controls endocrine and autonomic reactions which occur due to emotional triggers, along with behavioural expression of anxiety and fear.
The researchers found that acute optogenetic reactions of GABAergic neurons during non- rapid eye movement (NREM) sleep in mice led to wakefulness without the functions of orexins- neuropeptides important for maintaining wakefulness.
Prolonged excitation of GABAergic in BNST neurons by a chemogenetic method induced a longer-lasting, sustained wakefulness state, which was eliminated by pre-administration of a dual orexin receptor blocker, DORA 22.
The study reveals the role of the BNST GABAergic system in controlling sleep-wakefulness states, especially in shifting animals’ behavioural states from NREM sleep to wakefulness. It also provides an important insight into the pathophysiology of insomnia and the role of orexin in regulating wakefulness.
With this study there is a future in investigating drug treatments which can be administered to treat anxiety disorders which cause insomnia and restless sleep.
Source: The Journal of Neuroscience
