Though few things are as satisfying to me as a good night's sleep, it's becoming harder to achieve as I age. When I get insomnia, I feel like I've forgotten how to sleep!

Getting enough ZZZs is so important that all creatures need it, from insects to reptiles to mammals. When humans lack sleep, they're at risk for obesity, high blood pressure, and changes in cognitive function and behavior.

Most people have heard of REM ' or rapid eye movement ' sleep, but the process of sleep is a cycle with four stages of non-REM followed by one of REM sleep. As we sleep, our heart rate and core body temperature drop, and electrical activity in our brain changes.

In stage one, we drift in and out of wakefulness. In stages two and three we move into deeper sleep, and stage four is deep sleep, during which it is hard for a person to wake up. The final stage of the cycle is REM sleep, when both your brain and your eyes are most active.

REM starts about ninety minutes into sleep, and while in this stage, our heart rate and breath quicken and our eyes move irregularly because we're in dream mode. We should achieve full cycles of these stages several times a night. Even a few days without them alters our metabolism.

In experiments on sleep deprived rats, their bone formation was reduced, and the length of the small intestine as well as cholesterol levels both increased. We still don't fully understand the impact of chronic sleep debt on health.

Indeed, like we mentioned above, there's evidence that lack of sleep can alter our metabolism, causing changes in insulin signaling and in activities of genes in fat cells, which can contribute to obesity. Plus, our appetite goes up, which is my downfall!

Those are just some of the reasons we all need to practice good sleep hygiene - like not exercising too close to bedtime, no screen time for at least an hour before hitting the hay, and getting to bed around the same time nightly.