Sleep Control

There’s a reason we don’t have voluntary control over our sleep. Sleeping literally changes our very physiology. When we fall asleep our core body temperature drops which then allows certain proteins to work differently. It’s not something we'd want easy control over. The process of getting sleepy is highly regulated by not only our circadian rhythm but also by other hormone systems. We need to burn energy to feel fatigued (when we use ATP, we make adenosine as a byproduct, which signals fatigue in humans). We need a lack of blue-wavelength light to initiate the process of releasing melatonin at night, which makes us sleepy and helps initiate the sleeping-end of our circadian processes.

In short, we don't have voluntary control over our sleep because it's chemically and hormonally regulated.