-// Sleep returns the sleep log for date. Times are parsed in the user's timeozne, loc.
-func (c *Client) Sleep(ctx context.Context, date string, loc *time.Location) (*Sleep, error) {
+// Sleep returns the sleep log for date t. Times are parsed in the same timezone as t.
+func (c *Client) Sleep(ctx context.Context, t time.Time) (*Sleep, error) {