The human body when kept in an indoor environment of low lux light will not realize that it is daytime, as it cannot sense the increasing levels of daylight that the genetics are accustomed to. As such, by late morning your body may start sending a signal for you to sleep!

For some people, working and sleeping at high altitudes results in the hypoxia lobotomy.

I improved my sleeping circadian rhythm with red and infrared light exposures.

I lost my circadian rhythm during extreme night shift work atop the very high altitude mountain of Mauna Kea in Hawaii. Waking up in the morning, staying awake during the daytime and sleeping has been problematic ever since.

There was no monitoring of sleep in very high altitude workers that were sleeping at 9,200 feet. No warnings were given about high altitude induced sleep disorders.

Trying to get a good sleep at high altitude during the daytime between extreme night shifts generally required sleeping tablets.