According to an aspect, there is provided an apparatus (100) for assessing sleep of a subject, the apparatus comprising a processor (102) configured to: receive data indicative of one or more physiological parameters associated with a subject; determine, based on the data, two or more sleep parameters relating to sleep of the subject; and determine, based on the sleep parameters, whether the subject is suffering from (a) obstructive sleep apnoea, (b)
insomnia, (c) comorbid
insomnia and obstructive sleep apnoea, or (d) neither obstructive sleep apnoea nor
insomnia, wherein a first sleep parameter of the two or more sleep parameters comprises
Wakefulness After
Sleep Onset for at least X Minutes, WASOXmin, wherein WASOXmin comprises the sum of awakenings with a duration of X minutes or longer during a sleep session, wherein X is equal to, or greater than, 1.