Insight: Sleep is a free feature supplement in the journal Nature that looks at our latest knowledge about sleep.
How about that for a teaser:
On the contrary, the act of switching from being awake to sleeping can be extremely rapid, an observation that carries significant public health implications. And patients with various sleep disorders can exist in curious states that combine aspects of both sleep and wakefulness, indicating that the two are not always mutually exclusive.
The supplement is available here.