Are you exhausted with hard working?
Do you want to get more power for a long workday? When you feel like that, it's time to change your body condition and to boost the energy.
"Yawning" is your body and mind will be cool down. You need to try to yawn when you are tired.
See some red
Seeing some red color makes your brain clearly, and your muscles move faster and work harder.
Stretch it out
If you don't have time to exercise, but doing some easy stretches at home.
Are you smoking? Smoking using up your energy. The nicotine in tobacco is a stimulant, so it raises blood pressure and making it harder to fall asleep.