Sleepiness and insomnia

This weekend I was very sleepy all days.
During last week I had been staying up lately, by 1 am and waking up at 4 or 5 am, to make a teaching plan on Dec 30.
I was doing well even the shortage of sleeping time.

But this weekend, when I woke up at 6 am on Saturday, I felt a little fatigue and sleepy and it continued all day. So, Saturday night I went to bed more early and woke up at 6 am on Sunday morninig, and then, I felt fatigue again, besides it was more strong.

I was wondering why I've felt exhausted, even if I took enough rest.
One reason is that there is the missunderstanding of my biological clock by the irregular rhythm of life.
Making the rhythm of life into habit, our body make up a kind of a movement. The movement would drive smothly by the regular rhythm. In the other hand, it would confuse by the irregular rhythm. I guess, especially it would be connected to the wake-up switch.

The second is that the lightness is getting weak.
I've heard that sun could reset our body clock. Surely I often feel cloudy day. And recently, I've noticed some children have seasonal affected disorder. Eyes are sensitive acceptor. So, we might be infuenced by lightness as I thought.

The third is that today's temperature is comfortable for sleep. I think that there is sleep- inducing temperture.

The forth is that moderate fatigue cause drowsiness.

After all, I've found a lot of causes.
The other way, these ways would have good effects on the prevention of insomnia.