This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. A person who is involved in chronobiology.

"Charles Czeisler, another renowned sleep researcher and chronobiologist at Harvard Medical School, puts it more bluntly: Like a drunk, a person who is sleep-deprived has no idea how functionally impaired he or she truly is."