When we talk about things that you need to survive, food, water and shelter are at the top of the list. But another equally important commodity is sleep, which is a scarcity among college students. I mentioned the importance of sleep for studying and memory consolidation in my last column, but now it’s time to take a step back and talk about how the complexity of sleep and the lack of it impacts overall health and functioning.

Let me first explain brain waves. These emissions come from specialized brain cells called neurons when they fire at the same time. There are six kinds of brain waves, ranging from slow waves that occur during deep sleep to fast waves when we’re awake and solving complex problems.

There are several sleep stages characterized by brain activity. The exact number of these stages is disputed between sources, but they can essentially be broken into two categories: REM and non-REM sleep.

REM, or rapid eye movement, is the stage where the most vivid dreams occur and is defined by mixed, moderate–frequency brain waves that mimic wakefulness. While the purpose of REM sleep is largely unclear, some researchers consider it to be important for processing emotions.

The remaining stages occur in non-REM sleep; those include light sleep, deep sleep and the transitional stages between the two. Deep sleep is characterized by very slow waves and is considered the most restorative stage. Wave frequency increases as you move up through the stages.

Throughout the night, we progress through each stage — light sleep, transitional, deep sleep, light sleep, REM sleep — in one cycle and experience several cycles throughout the night depending on how long we’re asleep.

But how does your body know when to sleep? Your circadian rhythm is a fancy word for your 24-hour biological clock, and it is regulated by body temperature, hormones and environmental cues. For instance, the reduced exposure to sunlight in the evening signals the brain to release more of the hormone melatonin, causing sleepiness.

Many people ignore these nudges toward rest, and whether its due to work constraints or the release of your favorite show, it can still lead to sleep deprivation. Occasional sleep loss may only have small effects such as fatigue, irritability and forgetfulness. However, long–term deprivation can lead to chronic body pains, a weakened immune system and altered hormone levels. People in a deprived state go to sleep quicker but may skip REM and spend more time in deep sleep.

But all hope is not lost! If you have trouble sleeping, you may find some sleep-hygiene practices helpful. Reducing the consumption of caffeine, nicotine and heartburn-inducing foods in the evening helps you fall asleep faster. It’s also useful to avoid activities, other than sleeping, in your bed, especially stressful ones such as studying, watching TV or using your phone. However, I understand that college dorms aren’t designed with sleep hygiene in mind. Therefore, even small bedtime routines can help prepare your body and mind for rest.