It is said that nap is good to refresh our brain and feeling. Why is nap good for us?
When we are awake, our brain makes histamine and it excites brain. But when we fall asleep, sleep nerves works to reduces histamine and relaxes us.
The best sleep for nap is little deep one, starting to lose our strength and to lean. We should get up at this condition, otherwise we have a thick head. The best time for nap is 15 minutes and the best way is while we sit on chair.
I feel it is good to take nap on the train. 2Hz sway makes us sleepy and we can fall asleep moderately while we are sitting.