The causes of excessive daytime sleepiness include lacking sleep during the night and also some illnesses or their treatment. If someone is having chemotherapy this can cause sleepiness. Also if someone is not eating enough and they are starving this can cause sleepiness.
Ethanol- Depressant (Alcohol)
The short answer is, it increases melatonin production which causes sleepiness.
Nuvigil or Armodafinil is used to treat excessive sleepiness. It's a controlled substance with possible abuse potential, but it causes wakefulness, not sleepiness as narcotics do.
Tryptophan
body heat.
The following are some early signs of narcolepsy; excessive sleepiness during day time, a cataplexy or loss of muscle control, hallucinations, and sleep paralysis.
the position of the sun
The rotation of the Earth on its axis.
when you move and when the sun angle changes
when you move and when the sun angle changes
There are many medical reasons that could cause one to sleep all day. Some of these include thyroid problems, sleep apnoea, chronic fatigue syndrome, narcolepsy etc. Medication can also play a part in causing excessive day-time sleepiness.