I can't give you a magic number on this, but I can help you understand that sleep need is about how much and how good your sleep was last night; how sleep need differs for every individual and can differ for each individual every night; why tracking your sleep doesn’t tell you if you have met your sleep need; and how to “track” your sleep in a way that doesn't make your sleep worse.

For more info on James’ work go to www.thesleepgeek.co.uk