RMcCall
Explorer
Srasut knows that the desert definitely does not sleep at night. Sleeping means the team would probably be beset upon by scavenging desert lions or some similar creature. The ruins would be of use to such creatures who like to stalk their prey and approach unnoticed before pouncing. Stopping in the open would give much better warning of an attack, but also mean that the adventurers can't use anything for cover besides their own tents either. Continuing without sleep is an option, but it would make the team a bit weaker for whatever danger lies ahead.