According to The Sun, some of the key reasons we struggle to get out of bed include:
Altering bed times
Late nights and an ever-changing schedule of sleep times can mess with your circadian rhythm, which is created by the brain to determine when we feel sleepy.
Sleeping in on weekends
This can cause problems with your body clock, and can leave you with a feeling similar to jet lag.
It's in your genes
Scientists have pinpointed 15 genes that play a part in making someone a "morning person." Interestingly, early birds are also likely to have a thinner body shape than night owls.
Blame winter
As our sleep patterns are designed around light patterns, our body is programmed to be asleep when it's dark, which isn't so good for winter mornings.
-nzherald.co.nz