There’s a fascinating reason why it feels like it gets harder to sleep as you age

http://www.businessinsider.com/why-old-people-wake-up-early-2015-10

Infants sleep all day. Little kids get roughly 12 hours of sleep each night. But older people clock in just 7 nightly hours of shuteye. We need to sleep. It helps us process memories, learn new skills, and stabilize our mood. So what gives? Are we destined to get duller and more irritable the older we get? …

The difference between an older person’s and a younger person’s sleep schedule is relatively simple: Older people rarely get all their sleep in one solid block. As a result, they’re typically groggier after waking and take frequent naps.

In addition to sleeping less solidly, we also sleep less deeply as we age: The older we are, the less time our brains spend in deep sleep mode, that precious time when the frantic chaos of brain activity grinds to a slow burn.

A typical 25-year-old brain, for example, plunges half a dozen times into several hours of deep sleep throughout the night. In contrast, the average 70-year-old brain shuffles quickly in and out of moderate-level sleep, spending only a few minutes in the deepest phase of rest and far more time in shallow sleep or complete wakefulness. The transition between being asleep and awake also becomes far more abrupt as we age…

The relationship between the cells and sleep patterns was surprisingly precise: The fewer cells someone had, the more disrupted her sleep. And the more disrupted her sleep, the worse her memory. So what’s someone who wants to stay alert and happy to do?

Nap. Typically, naps still don’t allow us to reach deep sleep, but they do help make up for the decreases in alertness and increases in stress that can result from too little shuteye…

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