What is the solution to the problem of very heavy sleep, reaching 18 hours, which causes missing prayers, and does this entail sin?

It is recommended to consult doctors if sleep lasts for a long time, as it may be an illness. There is no sin upon one who misses prayer due to sleep, because the pen is lifted from the sleeper, and he must pray the missed prayers upon waking, as the Prophet, peace and blessings be upon him, said: "There is no negligence in sleep." One should take measures to wake up when sleeping before the prayer time.