Sleepiness

Sleepiness is a negative status effect caused by your hominid not sleeping enough.

Overview
Sleeping is a required function to keep your hominid alive. If you do not sleep for long enough, you will begin to have difficult performing actions and encounter Sleepiness.

The need for sleep will rise over time and the need to sleep will increase faster if your Hominid is hungry or  thirsty. If the need for sleep is high enough, the Hominid will get very sleepy. This is indicated by a screen fading out to black on and off again as if the Hominid was struggling to keep its eyes open.

While the screen fades black, your hearing will also be impaired and the "ping" sound needed for successful completion of tasks will not be heard anymore (or will be dampened). This can leave you very vulnerable to injury and death.

Learning specific neurons increases the positive benefits of sleeping.

Mechanics
Lie Down in a Sleep Spot or anywhere the Lie Down action appears. Press the appropriate button to go to sleep and this will allow you to replenish your Sleep.

Your hominid will begin to dream and time will pass. Your hominid will awaken once sleep has been completed.

Sleep spots are the most effective way to rest and they can be built anywhere. However, a spot where predators cannot get to you is highly recommenced as predators will sneak up on you as you sleep.

It is possible to be interrupted during sleep by hostile threats. While sleeping your hominid is exposed and cannot defend against attacks.