Which hormone relates with temperature and sleep-wake cycle?

The hormone $Melatonin$ is produced by the:

George comes on a vacation to India from the $U.S.$ The long journey disturbs his biological system and he suffers from jet lag. What is the cause of his discomfort?

The $24$ hour (diurnal) rhythm of our body,such as the sleep-wake cycle,is regulated by the hormone:

$P$ is a small,round,reddish structure located on the dorsal side of the forebrain. It contains a stalk and releases a hormone $Q$ which controls the diurnal rhythm of the body. $P$ and $Q$ are

The pineal gland is associated with: