It should be made clear that not everyone has a device to record their sleep patterns; in some of these nations, it's likely that only the richest people do.

必须要说清楚的是，并不是每个人都拥有一台记录他们睡眠模式的设备；在这些国家中的一些国家，可能只有最富有的人才能拥有这样一台设备。