半分起きて半分寝る～イルカの睡眠方法～

もし水族館などに行ってイルカを見る機会があったら目に注目すると、目を閉じてゆっくりと泳いでいるイルカがいる。人間が寝返りをうてるように、イルカは泳ぎながら眠ることが出来る。しかし中には片目を開けているイルカがいる。人間に限らず動物は普通、眠っている時は両目を閉じているが、片目だけが開いているというのはどのような状態なのか？実は片目だけを閉じているのは脳の半分だけが眠っている状態で、これはイルカなどの鯨類や渡り鳥が行なう半球睡眠という睡眠方法なのである。人間に限らず、多くの生物の脳は左右に分かれているが、その片方は起こして、開いている片目で周囲を警戒し、緊急時にすぐに行動できるようにしている。特に親イルカは子供が小さい頃は子供に向いている目を常に開けていて、文字通り片時も目を離さず見守っている。また、カモメやアホウドリなどの渡り鳥も半球睡眠をする。渡り鳥は季節によって住む場所を過ごしやすい気候の所に変えるが、その時に長距離を移動するので半球睡眠をしながら飛び続ける。

防御・安定:: 休眠

省エネ

警察や建物の警備など、長時間の待機が続き、緊急時には素早い行動が必要とされる状況で半球睡眠が出来れば、集中力を保ちつつ緊急時に素早く対応することが出来るようになる。また、生物によって脳の構造は多少違うが、脳が働く原理は基本的に同じと考えられている。ですから、イルカの睡眠のメカニズムを解明することで、ヒトの睡眠障害の治療に役立てることが出来るかもしれない。

Query	Affected	Num. rows	Took (ms)	Actions
SHOW FULL COLUMNS FROM `contents`	16	16	2	maybe slow
SELECT CHARACTER_SET_NAME FROM INFORMATION_SCHEMA.COLLATIONS WHERE COLLATION_NAME= 'utf8_general_ci';	1	1	1
SHOW FULL COLUMNS FROM `users`	10	10	1	maybe slow
SHOW FULL COLUMNS FROM `groups`	4	4	9	maybe slow
SHOW FULL COLUMNS FROM `permissions`	5	5	1	maybe slow
SHOW FULL COLUMNS FROM `groups_permissions`	3	3	1	maybe slow
SHOW FULL COLUMNS FROM `groups_users`	3	3	13	maybe slow
SHOW FULL COLUMNS FROM `contents_searches`	6	6	1	maybe slow
SHOW FULL COLUMNS FROM `attachments`	11	11	1	maybe slow
SHOW FULL COLUMNS FROM `attachments_revs`	13	13	1	maybe slow
SHOW FULL COLUMNS FROM `contents_related_items`	5	5	1	maybe slow
SHOW FULL COLUMNS FROM `related_items`	6	6	1	maybe slow
SHOW FULL COLUMNS FROM `contents_related_items_revs`	8	8	9	maybe slow
SHOW FULL COLUMNS FROM `contents_tags`	5	5	1	maybe slow
SHOW FULL COLUMNS FROM `tags`	7	7	1	maybe slow
SHOW FULL COLUMNS FROM `tag_groups`	6	6	1	maybe slow
SHOW FULL COLUMNS FROM `contents_tags_revs`	7	7	1	maybe slow
SHOW FULL COLUMNS FROM `contents_revs`	18	18	2	maybe slow
SELECT `Content`.`id`, `Content`.`user_id`, `Content`.`last_edit_user_id`, `Content`.`post_date`, `Content`.`post_date_year`, `Content`.`post_date_month`, `Content`.`post_date_day`, `Content`.`title`, `Content`.`title_en`, `Content`.`content`, `Content`.`plain_content`, `Content`.`page_view`, `Content`.`flag`, `Content`.`mod_count`, `Content`.`created`, `Content`.`modified` FROM `contents` AS `Content` WHERE `id` = 170 LIMIT 1	1	1	0
SELECT `Attachment`.`file_name`, `Attachment`.`dir`, `Attachment`.`model`, `Attachment`.`foreign_key` FROM `attachments` AS `Attachment` WHERE `file_name` <> 'default.jpg' AND `Attachment`.`foreign_key` = (170)	1	1	0
SELECT `ContentsRelatedItem`.`content`, `ContentsRelatedItem`.`related_item_id`, `ContentsRelatedItem`.`content_id` FROM `contents_related_items` AS `ContentsRelatedItem` WHERE `ContentsRelatedItem`.`content_id` = (170)	10	10	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 1	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 2	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 4	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 6	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 7	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 8	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 9	1	1	0
SELECT `RelatedItem`.`code`, `RelatedItem`.`name` FROM `related_items` AS `RelatedItem` WHERE `RelatedItem`.`id` = 11	1	1	0
SELECT `ContentsTag`.`id`, `ContentsTag`.`tag_group_id`, `ContentsTag`.`mod_count`, `ContentsTag`.`tag_id`, `ContentsTag`.`content_id` FROM `contents_tags` AS `ContentsTag` WHERE `ContentsTag`.`content_id` = (170)	2	2	1	maybe slow
SELECT `Tag`.`name`, `Tag`.`comment`, `Tag`.`tag_group_id` FROM `tags` AS `Tag` WHERE `Tag`.`id` = 88	1	1	0
SELECT `TagGroup`.`code`, `TagGroup`.`name` FROM `tag_groups` AS `TagGroup` WHERE `TagGroup`.`id` = 6	1	1	8	maybe slow
SELECT `Tag`.`name`, `Tag`.`comment`, `Tag`.`tag_group_id` FROM `tags` AS `Tag` WHERE `Tag`.`id` = 97	1	1	0
SELECT `TagGroup`.`code`, `TagGroup`.`name` FROM `tag_groups` AS `TagGroup` WHERE `TagGroup`.`id` = 7	1	1	0
SELECT `RelatedItem`.`id`, `RelatedItem`.`code`, `RelatedItem`.`name`, `RelatedItem`.`created`, `RelatedItem`.`modified`, `RelatedItem`.`flag` FROM `related_items` AS `RelatedItem` WHERE `code` = 'function' LIMIT 1	1	1	0
SELECT `Content`.`id`, `Content`.`title`, `Content`.`title_en` FROM `contents` AS `Content` WHERE id = (NULL) ORDER BY `id` desc	0	0	0

Message	Memory use
Component intitailization	6.79 MB
Controller action start	6.83 MB
Controller render start	6.90 MB
View render complete	7.92 MB

Message	Time in ms	Graph
Core Processing (Derived)	392.59
Component initialization and startup	10.32
Controller action	43.05
Render Controller Action	60.07
» Rendering View	48.08
» » Rendering APP/views/contents/view.ctp	28.19
» » Rendering APP/views/layouts/default.ctp	18.05
» » » Rendering APP/views/elements/header.ctp	1.56
» » » Rendering APP/views/elements/content_sidebar.ctp	0.46
» » » Rendering APP/views/elements/footer.ctp	0.41

半分起きて半分寝る～イルカの睡眠方法～

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半分起きて半分寝る ～イルカの睡眠方法～

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半分起きて半分寝る～イルカの睡眠方法～