Preventive measures to avoid Sleepbuds failing
Although Bose Sleepbuds is a great product, unfortunately a large fraction of them fail within weeks or months. It's probably a software failure, not a hardware one, but once they fail, there's no going back: they need to get replaced. Some users get their units replaced 3-4 times during the guarantee period or ask for a refund. If it's a software-related failure, then some measures could help to prevent problems (reduce the chance) in the first place.
(a) leaving the Sleepbuds on "Freephone mode" reduces the communication buds-phone, makes the buds more autonomic and thus reducing chances for a protocol problem;
(b) being extra-careful when placing the buds on the case, so they are always charging as expected, in pairs;
(c) do not load other background songs, use the standard ones;
(d) generally, use as few features as possible (e.g. alarms).
Despite these measures, the product is still great and I would recommend it to other users. Maybe Bose engineers cannot admit the product isn't 100% reliable, but it'd certainly help users to know from them which are the things users could do today to reduce the chance of problems in the future.