Science has revealed that our brain contains a master clock called the suprachiasmatic nucleus (SCN) which supposedly controls the activities of other “local” clocks that in turn regulate our metabolism and life processes. However, the lack of evidence of these local clocks has left the concept of biological clocks of wakefulness and sleep rather shrouded in mystery. A new study has fortunately defogged some of the layers preventing us from accessing information about these local clocks: they have come across one of these known as tuberomamillary nucleus (TMN) that is involved in the regulation of sleep and the awake state.
We are wired to wake up and sleep in cycles. Our bodies respond to light in such a way that we act upon the ‘messages’ that we receive to go to sleep, or to wake up. We have embedded in our biological systems what are known as circadian clocks that tune us to wake up and sleep at the required time. However, evidence to substantiate these theories has been hard to find. Until now.
A team of scientists think that they have laid their hands onto the secret of biological clocks. They have examined a local clock tuberomamillary nucleus (TMN) situated in a part of the brain. The TMN has a number of histaminergic neurones that remain inactive during sleep. During wakefulness, it releases histamine which keeps the body in an active state. They have manipulated the histaminergic neurones of lab mice by deleting a ‘clock’ gene known as Bmal1. This deletion led the mice to produce greater levels of the enzyme that triggers the production of histamine, and as a result, the animals stayed awake for longer periods than they normally would have.
Another effect that was observed was that the mice had more fragmented sleep, less deep sleep, and delayed recovery from sleeplessness. The scientists explained that these responses hint at the presence of an active clock-like mechanism embdeed in the histaminergic neurons, thus showing that local clocks work simultaneously with the previously-known major SCN clock.
One of the authors said in a statement:
“Our work with mice suggests that local body clocks play a key role in ensuring their sleeping and waking processes work properly. When a local clock was disrupted, their whole sleep and wake system malfunctioned. Ultimately, understanding local clocks better might enable us to target them to help people have a better night’s sleep.”