Pineal Gland

We all sleep at night and then wake up in the morning, right.

And this cycle repeats itself everyday.

Some of us need an alarm clock to wake up while many others do not.

It seems that our body has an internal clock which tells when to wake up and sleep.

This internal clock of our body is actually a very tiny endocrine gland.

This endocrine gland is known as the pineal gland.

The word ‘pineal’ comes from a latin word, ‘pinea’ which refers to pine.

And as the word suggests, the pineal gland is also shaped like a pine.

It is located near the centre of the brain, in the dorsal part of the forebrain.

Like other endocrine glands, it also secretes a hormone.

This hormone is known as melatonin.

This hormone actually controls the wake-sleep cycle of our body.

And the way melatonin does so is very interesting. Let's have a look at it.

The level of light received from the environment controls the production of melatonin.

We know that the retina of our eyes can sense the intensity of light( how much light is present in our surrounding).

It then sends a message to the brain in the form of an impulse.

This message is received by the pineal gland and depending on the message, it either secretes melatonin or stops its secretion.

Let’s see how melatonin production affects our wake-sleep cycle.

During night time, the pineal gland starts secreting large amounts of melatonin.

High melatonin levels causes drowsiness and tiredness and so, we fall asleep.

Whereas, when the light levels increase, the secretion of melatonin gets lowered down.

Hence, we wake up in the morning and are more active.

Melatonin secretion also depends on the seasonal changes in light levels.

Getting out of bed on a dull, rainy morning can be so difficult due to this reason.

Melatonin also serves other functions. Let’s have a look at them.

It helps in regulating our body temperature and metabolic processes.

It also controls the onset (beginning) of puberty in humans.

It also regulates the beginning of menstrual cycle in women.

It also influences melanin production and hence controls skin pigmentation.


The pineal gland is located on the dorsal side of forebrain.

It secretes a hormone called melatonin.

Melatonin regulates the wake-sleep cycle of our body.

The End