user14372: I need to put arduino in sleep mode. I did not find the library avr/sleep.h . From where to download it. 

user4143: avr/sleep.h is part of the compiler. You don't need to download it.
There are other libraries that act as a wrapper to it to make life easier:

https://github.com/lowpowerlab/lowpower
https://github.com/rocketscream/Low-Power


14372: <p>I need to put arduino in sleep mode. I did not find the library avr/sleep.h . From where to download it. </p>
 4143: <p><code>avr/sleep.h</code> is part of the compiler. You don't need to download it.</p>

<p>There are other libraries that act as a wrapper to it to make life easier:</p>

<ul>
<li><a href="https://github.com/lowpowerlab/lowpower" rel="nofollow">https://github.com/lowpowerlab/lowpower</a></li>
<li><a href="https://github.com/rocketscream/Low-Power" rel="nofollow">https://github.com/rocketscream/Low-Power</a></li>
</ul>
