People with depression often have hypersomnia, or excessive sleep, but still feel tired during the day. why might this be?

a. they tend to have less deep sleep and their rem sleep is less stable.
b. they tend to have no deep sleep, though their rem sleep is more stable.
c. they tend to have more deep sleep and their rem sleep is less stable.

i think it's they tend to have more deep sleep and their Rem sleep is less stable.

because you are not supposed to sleep more than your normal sleep time so if you over sleep you will still be tired if you get to less of a sleep then you are going to be still a little tired just not as much if you were to over sleep

Explanation:

so i hope this helps :))

so i think its the last one